Method for performing carrier management procedure in a multi-carrier supported wideband wireless communication system and apparatus for the same

ABSTRACT

A method and apparatus for performing carrier management in a broadband wireless communication system supporting multiple carriers are disclosed. The method for a mobile station to perform carrier management procedure with a base station supporting multiple carriers includes receiving a carrier management command message from the base station, the carrier management command message including an action code for carrier management and a polling bit in a MAC Control Extended Header (MCEH) indicating whether an acknowledgement message is required, transmitting the acknowledgement message in response to the carrier management command message to the base station when the carrier management command message is successfully received and the polling bit is set to 1, and transmitting a carrier management indication message corresponding to the action code included in the carrier management command message to the base station.

This application claims the benefit of U.S. Provisional PatentApplication Nos. 61/229,270, filed on Jul. 28, 2009, 61/232,475, filedon Aug. 10, 2009, 61/237,271, filed on Aug. 26, 2009, 61/250,883, filedon Oct. 13, 2009, 61/260,395, filed on Nov. 11, 2009, 61/265,764, filedon Dec. 2, 2009, 61/286,767, filed on Dec. 15, 2009, and Korean PatentApplication No. 10-2010-0027898, filed on Mar. 29, 2010, which arehereby incorporated by reference as if fully set forth herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a broadband mobile communicationsystem, and more particularly to a method and apparatus for performing acarrier management procedure in a broadband wireless communicationsystem supporting multiple carriers.

2. Discussion of the Related Art

A base station (BS) for use in a conventional wireless communicationsystem includes a single PHY (physical layer) entity capable ofsupporting a single frequency channel (or a single carrier), and asingle Medium Access Control (MAC) controller for controlling the singlePHY entity may be provided to the base station (BS). In addition, aplurality of MAC-PHY entities may be present in a single cell. A mobilestation (MS) that is capable of exchanging data with the base station(BS) by a single MAC-PHY entity during a certain transmission timeinterval (TTI), may be referred to as a single-carrier supported MS.

In recent times, a multi-carrier supported wireless communication systemsuch as a multi-carrier aggregation has been proposed to allow the MS toexchange data with the BS through a plurality of carriers.

Multi-carrier aggregation technology achieves data communication betweena mobile station (MS) and a base station (BS) through a plurality ofaggregations of bandwidth-based carriers that are defined in aconventional wireless communication system (IEEE 802.16e in an IEEE802.16m system or a Long Term Evolution (LTE) in a Long TermEvolution—Advanced (LTE-A) system). FIGS. 1( a) and 1(b) illustratecontiguous carrier aggregation and non-contiguous carrier aggregation,respectively.

In a multi-carrier supported system, a plurality of frequency channelsmay be controlled by a single common MAC as necessary. If the frequencychannels are controlled by the single common MAC, some MAC messagestransmitted via a single carrier can also be applied to other carriers.

Carriers associated with operations of a multi-carrier mode may beclassified into a primary carrier and a secondary carrier. The primarycarrier may allow the base station (BS) to exchange traffic and PHY/MACcontrol signaling (e.g., MAC control message) with the mobile station(MS). Although the multi-carrier supported MS is used, it can be definedthat the multi-carrier supported MS has only one primary carrier asnecessary. The secondary carrier is an additional carrier used by themobile station (MS) for traffic, and may be used according to a specificcommand by the base station (BS) and rules that are received through theprimary carrier.

MAC control messages for carrier management may be defined. For example,an Advanced Air Interface Carrier Management Command (AAI_CM-CMD)message and an Advanced Air Interface Carrier Management Indication(AAI_CM-IND) message are defined in an IEEE 802.16m standardspecification. By the AAI_CM-CMD message received from the base station(BS), primary carrier change, secondary carrier management (secondarycarrier activation and/or deactivation), and carrier switching may beperformed. The AAI_CM-IND message is a MAC control message used as aresponse to the AAI_CM-CMD message, and is transmitted from the mobilestation (MS) to the base station (BS).

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a method forperforming a carrier management procedure in a multi-carrier supportedbroadband wireless communication system and an apparatus for the same,that substantially obviate one or more problems due to limitations anddisadvantages of the related art.

Assuming that an unexpected fault occurs in a carrier managementprocedure, such as carrier change or carrier activation and/ordeactivation, for use in a multi-carrier supported system, the fault maynegatively affect communication between the mobile station (MS) and thebase station (BS). Occasionally, it may be impossible to achievecommunication between the mobile station (MS) and the base station (BS).

Therefore, in the carrier management procedure, a carrier managementcommand and an acknowledgement response to the carrier managementcommand should be certainly operated, and carrier activation and/ordeactivation caused by the carrier management command should be achievedat correct time point(s).

In addition, considering that a plurality of carriers is controlled by acommon MAC in a multi-carrier supported system, it is necessary todevise a new method for allowing a single-carrier supported MS to moreeffectively perform a carrier change operation.

An object of the present invention is to provide a method foreffectively transmitting a carrier management message and a method foreffectively performing carrier management in a carrier managementprocedure of a multi-carrier supported wireless communication system.

Another object of the present invention is to provide an effectivecarrier change method of a single-carrier supported mobile station (MS)for use in a multi-carrier supported wireless communication system.

The object of the present invention can be achieved by providing amethod for a mobile station to perform carrier management procedure witha base station supporting multiple carriers, the method comprising:receiving a carrier management command message from the base station,the carrier management command message including an action code forcarrier management and a polling bit in a MAC Control Extended Header(MCEH) indicating whether an acknowledgement message is required,transmitting the acknowledgement message in response to the carriermanagement command message to the base station when the carriermanagement command message is successfully received and the polling bitis set to 1, and transmitting a carrier management indication messagecorresponding to the action code included in the carrier managementcommand message to the base station.

The carrier management indication message is transmitted to the basestation to inform the base station that a target carrier indicated bythe carrier management command message is ready for signal transmissionand reception.

The acknowledgement message is a message acknowledgement (AAI_MSG-ACK)message or a message acknowledgement extended header (MAEH).

If the action code indicates primary carrier change, the acknowledgementmessage in response to the carrier management command message istransmitted on a serving primary carrier of the base station, and thecarrier management indication message is transmitted on a target primarycarrier of the base station.

If the action code is primary carrier change, the carrier managementindication message is transmitted on a target primary carrier of thebase station when the primary carrier change is successful, and thecarrier management indication message is transmitted on a servingprimary carrier of the base station when the primary carrier change isnot successful.

The carrier management indication message is transmitted through bandrequest on the serving primary carrier of the base station when theprimary carrier change is not successful and the serving primary carrieris deactivated.

In another aspect of the present invention, provided herein is a methodfor a base station supporting multiple carriers to perform carriermanagement procedure with a mobile station, the method comprising:transmitting a carrier management command message to the mobile station,the carrier management command message including an action code forcarrier management and a polling bit in a MAC Control Extended Header(MCEH) indicating whether an acknowledgement message is required,receiving the acknowledgement message in response to the carriermanagement command message from the mobile station when the carriermanagement command message is successfully received by the mobilestation and the polling bit is set to 1, and receiving a carriermanagement indication message corresponding to the action code includedin the carrier management command message from the mobile station.

The carrier management method may further include starting aretransmission timer at a transmission time of the carrier managementcommand message, stopping the retransmission timer and performing anoperation corresponding to the action code when the acknowledgementmessage is received prior to the expiration of the retransmission timer,and retransmitting the carrier management command message when noacknowledgement message is received prior to the expiration of theretransmission timer.

The carrier management indication message is received from the mobilestation to inform the base station that a target carrier indicated bythe carrier management command message is ready for signal transmissionand reception.

The acknowledgement message is a message acknowledgement (AAI_MSG-ACK)message or a message acknowledgement extended header (MAEH).

If the action code indicates primary carrier change, the acknowledgementmessage in response to the carrier management command message isreceived on a serving primary carrier from the mobile station, and thecarrier management indication message is received on a target primarycarrier from the mobile station.

If the action code is primary carrier change, the carrier managementindication message is received on a target primary carrier from themobile station when the primary carrier change is successful, and thecarrier management indication message is received on a serving primarycarrier from the mobile station when the primary carrier change is notsuccessful.

The carrier management indication message is received through bandrequest on the serving primary carrier from the mobile station when theprimary carrier change is not successful and the serving primary carrieris deactivated.

In another aspect of the present invention, provided herein is a mobilestation for performing a carrier management procedure with a basestation supporting multiple carriers, the mobile station comprising: areception module for receiving a downlink control signal and downlinkdata from the base station, a transmission module for transmitting anuplink control signal and uplink data to the base station, and aprocessor connected to the reception module and the transmission modulefor controlling the mobile station including the reception module andthe transmission module, wherein the processor is configured to: controlthe reception module to receive a carrier management command messagefrom the base station, the carrier management command message includingan action code for carrier management and a polling bit in a MAC ControlExtended Header (MCEH) indicating whether an acknowledgement message isrequired, control the transmission module to transmit theacknowledgement message in response to the carrier management commandmessage to the base station when the carrier management command messageis successfully received and the polling bit is set to 1, control themobile station to perform carrier management operation based on thecarrier management command message, and control the transmission moduleto transmit a carrier management indication message corresponding to theaction code included in the carrier management command message to thebase station.

In another aspect of the present invention, provided herein is a basestation supporting multiple carriers for performing a carrier managementprocedure with a mobile station, the base station comprising: areception module for receiving an uplink control signal and uplink datafrom the mobile station, a transmission module for transmitting adownlink control signal and downlink data to the mobile station, and aprocessor connected to the reception module and the transmission modulefor controlling the base station including the reception module and thetransmission module, wherein the processor is configured to: control thetransmission module to transmit a carrier management command message tothe mobile station, the carrier management command message including anaction code for carrier management and a polling bit in a MAC ControlExtended Header (MCEH) indicating whether an acknowledgement message isrequired, control the reception module to receive the acknowledgementmessage in response to the carrier management command message from themobile station when the carrier management command message issuccessfully received by the mobile station and the polling bit is setto 1, control the reception module to receive a carrier managementindication message corresponding to the action code included in thecarrier management command message from the mobile station.

The exemplary embodiments of the present invention have the followingeffects.

In association with a carrier management procedure for use in amulti-carrier supported wireless communication system, the embodiment ofthe present invention provides a method for effectively transmitting acarrier management message and a method for effectively performingcarrier management.

In association with a multi-carrier supported wireless communicationsystem, the embodiment of the present invention provides an effectivecarrier change method of a single carrier supported MS.

It will be appreciated by persons skilled in the art that that theeffects that can be achieved with the present invention are not limitedto what has been particularly described hereinabove and other advantagesof the present invention will be more clearly understood from thefollowing detailed description taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention, illustrate embodiments of the inventionand together with the description serve to explain the principle of theinvention. In the drawings:

FIGS. 1( a) and 1(b) illustrate contiguous carrier aggregation andnon-contiguous carrier aggregation, respectively.

FIGS. 2( a) and 2(b) illustrate a MAC-PHY entity structure and a commonMAC, respectively.

FIG. 3 illustrates the relationship among an available carrier, anassigned carrier, and an active carrier in a multi-carrier system.

FIGS. 4( a) and 4(b) are flowcharts illustrating message exchange inresponse to a carrier management procedure.

FIG. 5 is a flowchart illustrating usages of an acknowledgement messagefor use in a secondary carrier management procedure according to oneembodiment of the present invention.

FIGS. 6( a) and 6(b) are flowcharts illustrating usages of anacknowledgement message for use in a primary carrier change procedureaccording to one embodiment of the present invention.

FIG. 7 is a conceptual diagram illustrating the relationship between anaction time and a retransmission timer for use in a primary carrierchange procedure according to one embodiment of the present invention.

FIG. 8 illustrates a disconnection time for use in a secondary carriermanagement procedure according to one embodiment of the presentinvention.

FIGS. 9( a), 9(b) and 9(c) illustrate general handover procedures.

FIGS. 10( a), 10(b) and 10(c) illustrate common MAC handover proceduresof a single-carrier mobile station (MS) through a handover procedureaccording to one embodiment of the present invention.

FIG. 11 is a flowchart illustrating mobile station (MS) operation duringnetwork re-entry from among a common MAC handover according to oneembodiment of the present invention.

FIG. 12 is a flowchart illustrating common MAC handover procedures of asingle-carrier MS through a handover procedure according to oneembodiment of the present invention.

FIG. 13 is a flowchart illustrating common MAC handover procedures of asingle-carrier MS through a multi-carrier associated MAC control messageaccording to one embodiment of the present invention.

FIGS. 14( a), 14(b) and 14(c) illustrate common MAC handover proceduresof a single-carrier MS using a multi-carrier associated MAC controlmessage according to another embodiment of the present invention.

FIG. 15 is a flowchart illustrating an MS initialization action for usein a network entry process according to one embodiment of the presentinvention.

FIG. 16 is a flowchart illustrating an MS initialization action for usein a network entry process according to another embodiment of thepresent invention.

FIG. 17 illustrates functional blocks of a mobile station (MS) accordingto one embodiment of the present invention.

FIG. 18 illustrates functional blocks of a base station (BS) accordingto another embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings.

Exemplary embodiments described hereinbelow are combinations of elementsand features of the present invention. The elements or features may beconsidered selective unless otherwise mentioned. Each element or featuremay be practiced without being combined with other elements or features.Further, an embodiment of the present invention may be constructed bycombining parts of the elements and/or features. Operation ordersdescribed in embodiments of the present invention may be rearranged.Some constructions of any one embodiment may be included in anotherembodiment and may be replaced with corresponding constructions ofanother embodiment.

In exemplary embodiments of the present invention, a description is madeof a data transmission and reception relationship between a Base Station(BS) and a Mobile Station (MS). Herein, the term ‘BS’ refers to aterminal node of a network, which directly communicates with the MS. Insome cases, a specific operation described as performed by the BS may beperformed by an upper node of the BS.

Namely, it is apparent that, in a network comprised of a plurality ofnetwork nodes including a BS, various operations performed forcommunication with an MS may be performed by the BS, or network nodesother than the BS. The term ‘BS’ may be replaced with the term ‘fixedstation’, ‘Node B’, ‘eNode B (eNB)’, ‘access point’, or ‘Advanced BaseStation (ABS) that is supported by an IEEE 802.6m system, etc. Inaddition, the term ‘relay’ may be replaced with a Relay Node (RN), aRelay Station (RS) or the like. The term ‘MS’ may be replaced with theterm ‘User Equipment (UE)’, Subscriber Station (SS), ‘Mobile SubscriberStation (MSS)’, ‘mobile terminal’, or ‘Advanced Mobile Station (AMS)’that is supported by an IEEE 802.16m system, etc.

Specific terms used for the exemplary embodiments of the presentinvention are provided to help in understanding of the presentinvention. These specific terms may be replaced with other terms withinthe scope and spirit of the present invention.

In some cases, in order to prevent ambiguity of the concepts of thepresent invention, conventional devices or apparatuses well known tothose skilled in the art will be omitted and be denoted in the form of ablock diagram on the basis of the important functions of the presentinvention. Wherever possible, the same reference numbers will be usedthroughout the drawings to refer to the same or like parts.

Exemplary embodiments of the present invention are supported by standarddocuments disclosed for at least one of wireless access systemsincluding an Institute of Electrical and Electronics Engineers (IEEE)802 system, a 3^(rd) Generation Project Partnership (3GPP) system, a3GPP Long Term Evolution (LTE) system, and a 3GPP2 system. Inparticular, the steps or parts, which are not described to clearlyreveal the technical idea of the present invention, in the embodimentsof the present invention may be supported by the above documents. Allterminology used herein may be supported by at least one of theabove-mentioned documents.

The following embodiments of the present invention can be applied to avariety of wireless access technologies, for example, CDMA (CodeDivision Multiple Access), FDMA (Frequency Division Multiple Access),TDMA (Time Division Multiple Access), OFDMA (Orthogonal FrequencyDivision Multiple Access), SC-FDMA (Single Carrier Frequency DivisionMultiple Access), and the like. The CDMA may be embodied with wireless(or radio) technology such as UTRA (Universal Terrestrial Radio Access)or CDMA2000. The TDMA may be embodied with wireless (or radio)technology such as GSM (Global System for Mobile communications)/GPRS(General Packet Radio Service)/EDGE (Enhanced Data Rates for GSMEvolution). The OFDMA may be embodied with wireless (or radio)technology such as Institute of Electrical and Electronics Engineers(IEEE) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802-20, and E-UTRA(Evolved UTRA). The UTRA is a part of the UMTS (Universal MobileTelecommunications System). The 3GPP (3rd Generation PartnershipProject) LTE (long term evolution) is a part of the E-UMTS (EvolvedUMTS), which uses E-UTRA. The 3GPP LTE employs the OFDMA in downlink andemploys the SC-FDMA in uplink. The LTE-Advanced (LTE-A) is an evolvedversion of the 3GPP LTE. WiMAX can be explained by an IEEE 802.16e(WirelessMAN-OFDMA Reference System) and an advanced IEEE 802.16m(WirelessMAN-OFDMA Advanced System). For clarity, the followingdescription focuses on the IEEE 802.16m. However, technical features ofthe present invention are not limited thereto.

MAC-PHY Entity and Common MAC

A MAC-PHY entity will hereinafter be described with reference to FIGS.2( a) and 2(b). FIGS. 2( a) and 2(b) illustrate a MAC-PHY entitystructure and a common MAC, respectively.

FIG. 2( a) shows a MAC-PHY entity for use in a conventional wirelesscommunication system. A base station (BS) for use in a conventionalwireless communication system includes a single PHY entity 220supporting a single frequency channel, and a single MAC controller 210for controlling the single PHY entity 220 may be provided to the basestation (BS). A plurality of MAC-PHY entities may be present in one cell(cell_1 or cell_2). A mobile station (MS) capable of exchanging datawith the base station (BS) through one MAC-PHY entity during apredetermined transmission time interval (TTI) may be referred to as asingle-carrier supported mobile station (MS).

FIG. 2( b) shows a MAC-PHY entity for use in a multi-carrier supportedwireless communication system. The multi-carrier supported wirelesscommunication system means a wireless communication system for providinga specific technology to the mobile station (MS) such that the mobilestation (MS) can exchange data with the base station (BS) simultaneouslyusing a plurality of carriers during an arbitrary TTI. The multi-carriersupported system may allow a plurality of frequency channels to becontrolled by a single common MAC. A single MAC entity 230 is present inone cell (cell_1 or cell_2), and each frequency channel of the PHYentity 240 may be controlled by a single common MAC entity 230. That is,the common MAC entity 230 may control the PHY entity 240 having therange of a plurality of frequency channels.

The multi-carrier supported base station (BS) may include not only theconventional MAC-PHY entity supporting a single frequency channel butalso a MAC-PHY entity comprised of the above-mentioned common MAC. Inaddition, each of the common MAC and a MAC may include a single basestation identifier (BSID). The operation, in which an MS that iscurrently receiving a service from a certain MAC changes its ownfrequency channel to that of another MAC having a different BSID, may bedefined as an inter-frequency handover (HO). The other operation, inwhich a frequency channel of the MS that is currently receiving theservice from a certain MAC changes is changed to another frequencychannel within the range of one common MAC, may be defined as ‘primarycarrier change’.

Under the control of a common MAC, some MAC messages transmitted througha single carrier may be applied to other carriers. Some frequencychannels may have different bandwidths (e.g., 5 MHz, 10 MHz and 20 MHz),and may be present in contiguous or non-contiguous frequency bands. Thefrequency channels may have different duplex modes, and each frequencychannel may support Frequency Division Duplexing (FDD), Time DivisionDuplexing (TDD), or a combination mode of two-way and broadcastdedicated carriers. The MAC entity can support the co-existence ofmobile stations (MSs) having different capabilities, such that it may beoperated by only one channel at one time or may support capabilitiessuch as contiguous/non-contiguous channel aggregation. Therefore,multiple frequency channels can be more easily controlled by the commonMAC supporting multi-carrier aggregation.

Multiple carriers contained in the same common MAC can be simultaneouslyused by a base station (BS) and a mobile station (MS). In order to allowthe mobile station (MS) to more effectively use the concept of multiplecarriers, the embodiment of the present invention provides a carriermanagement method (e.g., secondary carrier management, primary carrierchange, and carrier switching).

Multi-Carrier Types and Operation Modes

From the viewpoint of a mobile station (MS), carriers associated withthe multi-carrier mode operation may be classified into a primarycarrier and a secondary carrier. The primary carrier refers to a carrierthat is used when a base station (BS) exchanges traffic and PHY/MACcontrol signaling (e.g., MAC control message) with the mobile station(MS). Although multiple carriers may be used in the base station (BS),the mobile station (MS) belonging to the BS has only one primarycarrier. In addition, the primary carrier is also used even when themobile station (MS) is operated in a single carrier mode. Meanwhile, thesecondary carrier refers to an additional carrier that is used by themobile station (MS) for traffic, and may be used according to a specificcommand by the base station (BS) and rules received through the primarycarrier.

In relation to an FDD mode and a TDD mode, a carrier may refer to adownlink or uplink physical frequency channel. The physical carrierindexes may refer to indexes of an available carrier of the base station(BS), and are arranged in ascending numerical order from a low frequencyto a high frequency.

During the multi-carrier operation, the common MAC can fully control themobility, status and context of the MS through the primary carrier, andat the same time can use radio resources of the primary carrier and atleast one secondary carrier.

Based on the usages and services of the primary carrier and/or thesecondary carrier, carriers of the multi-carrier system can beclassified into a fully configured carrier and a partially configuredcarrier. The fully configured carrier is a standalone carrier, andrefers to a carrier in which all control channels includingsynchronization, broadcast, multicast and unicast control signaling areconfigured. The fully configured carrier can support not only the singlecarrier mobile station (MS) but also the multi-carrier mobile station(MS). Meanwhile, the partially configured carrier refers to either acarrier for downlink dedicated transmission in TDD mode or a downlinkcarrier that is unpaired with an uplink carrier in FDD mode. Thesecondary carrier may only be used in conjunction with the primarycarrier, and cannot be independently operated to provide an Advanced AirInterface (AAI) service to the mobile station (MS). Informationindicating whether the carrier is a fully configured carrier or apartially configured carrier is indicated by a preamble of a carrier(i.e., advanced preamble). The mobile station (MS) does not attempt toperform a network entry or a handover (HO) for the partially configuredcarrier. In the multi-carrier aggregation, an uplink control channel,that is used as a secondary carrier and corresponds to the partiallyconfigured carrier, may be located at a control area that is notoverlapped with an uplink of the primary carrier. In order to feed backnot only information about HARQ ACK/NACK corresponding to transmissionthrough a downlink-dedicated secondary carrier but also channel qualitymeasurement, an uplink control channel on the primary carrier is used.

The secondary carrier may be a fully configured carrier or a partiallyconfigured carrier according to the usage plan, whereas the primarycarrier is always a the fully configured carrier. Assuming that thesecondary carrier for a certain mobile station (MS) is a fullyconfigured carrier, this secondary carrier may be used as a primarycarrier of another mobile station (MS) as necessary. Several mobilestations (MSs) having different primary carriers may share the samesecondary carrier. In relation to the above description, themulti-carrier operations, such as a multi-carrier aggregation and amulti-carrier switching, etc. may be independently or simultaneouslysupported.

The multi-carrier aggregation means that the MS maintains the connectionto a physical layer, monitors control signaling on the primary carrier,and at the same time processes data on the secondary carrier. Resourceallocation for the mobile station (MS) may have the range of the primarycarrier and several secondary carriers. The link adaptation feedbackmechanism may include measurement of both the primary carrier and thesecondary carrier. In a multi-carrier aggregation mode, according tosystem load (i.e., static/dynamic load balancing), peak data rate, orQoS (Quality of Service) request, a system may asymmetrically allocate asecondary carrier to a mobile station (MS) through a downlink and/or anuplink.

The multi-carrier switching may refer to a multi-carrier mode in which amobile station (MS) switches the connection to the physical layer fromthe primary carrier to the secondary carrier upon receiving anindication message from the base station (BS). The mobile station (MS)connects to the secondary carrier during a predetermined time interval,and returns to the primary carrier. Assuming that the mobile station(MS) connects to the secondary carrier, the mobile station (MS) may notmaintain transmission/reception through the primary carrier. Theabove-mentioned mode may be used for the switching to either thepartially configured carrier or the fully configured carrier, such thatan Enhanced Multicast Broadcast Service (E-MBS) can be received.

The following descriptions may be commonly applied to the multi-carriermode operations.

A system may define N independent and fully-configured carriers. In eachof the N independent and fully-configured carriers, synchronization,broadcast, and multicast and unicast control signaling channels neededto support the single carrier mode MS are configured. Each mobilestation (MS) contained in the cell is connected to only one fullyconfigured carrier that is set to the primary carrier, and the status ofthe mobile station (MS) can be controlled through the primary carrier.In addition, the system may define M partially configured carriers(where M≧0), and each carrier may be used only as the secondary carrierinstead of the primary carrier, and may be used to transmit downlinkdedicated data.

FIG. 3 illustrates the relationship among an available carrier, anassigned carrier, and an active carrier in a multi-carrier system. Asshown in FIG. 3, the aggregate of all carriers supported by a basestation (BS) may be referred to as an available carrier (310). A carrierthat is allocated as a partial aggregation of the available carriers tothe mobile station (MS) may be referred to as an assigned carrier (320).A carrier that is used as a partial aggregation of the assigned carriersand is ready to be used for multi-carrier allocation may be referred toas an active carrier (330).

The available carriers may be located at different parts of the samespectrum block or at non-contiguous spectrum blocks. The base station(BS) may provide not only information of a primary carrier (i.e., aserving primary carrier) but also a few setup information segments ofavailable carriers through the primary carrier. Through theabove-mentioned messaging, the base station (BS) indicates the MS'sexistence, bandwidth, duplexing, and spectrum positions of all availablecarriers, such that it enables the mobile station (MS) to prepare forall kinds of multi-carrier operations. In addition, the primary carriermay further provide the extended information about the secondary carriersetup as necessary.

Network Entry

Network entry from among MAC actions related to multi-carrier operationswill hereinafter be described in detail.

In the multi-carrier mode, network entry is basically identical to thatin single carrier mode. During the registration process of a basestation (BS) and a mobile station (MS), the base station (BS) and themobile station (MS) may display whether or not the multi-carrier mode issupported. The mobile station (MS) can perform network entry (or networkre-entry) only through the fully configured carrier. In the case wherethe mobile station (MS) detects ‘A-PREAMBLE’ on the fully configuredcarrier, the mobile station (MS) can read a super-frame header (SFH), anextended system parameter, and system setup information.

During initial network entry, the mobile station (MS) transmits anAdvanced Air Interface Registration Request (AAI_REG-REQ) message to thebase station (BS) such that the mobile station (MS) informs the basestation (BS) that the mobile station (MS) supports multi-carriertransmission. The base station (BS) transmits an AAI registrationresponse (AAI_REQ-RSP) message to the mobile station (MS) such that itcan display whether there is a supported mode from among multi-carriermodes associated with the mobile station (MS). The basic multi-carriercapability exchange may use 2-bit codes of the AAI_REQ-REQ/AAI_REQ-RSPmessages as shown in the following Table 1.

TABLE 1 b1, b2 Multicarrier Capabilities 00 No MC modes 01 Basic MC mode10 Multicarrier Aggregation 11 Multicarrier Switching

A basic multi-carrier mode (Basic MC mode) includes a mobile station(MS) operation in which the mobile station (MS) is aware of BS'smulti-carrier (MC) operations which include primary carrier change and asupport of MC-associated optimization scanning. Supporting both themulti-carrier aggregation and the multi-carrier (MC) switching may notrepresent the support of an Enhanced Multicast Broadcast Service(E-MBS), and may be separately negotiated as necessary.

The mobile station (MS) initialization procedure for preparing for thesubsequent multi-carrier (MC) action after network entry willhereinafter be described. The mobile station (MS) initializationprocedure may include an operation for acquiring multi-carrier (MC)setup information about available carriers of the base station (BS) andan operation for acquiring information about assigned carriers.Acquisition of the assigned carrier information may provide the basestation (BS) with information about supported carriers of the mobilestation (MS) and information about the combined multi-carrier (MC)setup. In the subsequent MC action of the above mobile station (MS), thebase station (BS) can acquire information about a partial aggregation(i.e., assigned carrier) of available carriers of the base station (BS).

The mobile station (MS) does not perform the MAC or PHY processingthrough the assigned carrier before the assigned carrier is activated bya command received from the base station (BS).

Carrier Management

First, activation or deactivation of the secondary carrier willhereinafter be described in detail. Activation or deactivation of thesecondary carrier may be determined by a base station (BS) on the basisof a QoS (Quality of Service), load condition of a carrier and otherfactors. The base station (BS) may activate and/or deactivate thesecondary carrier using an AAI Carrier Management Command (AAI_CM-CMD)message. The base station (BS) may transmit the AAI_CM-CMD messagethrough the primary carrier, wherein the AAI_CM-CMD message includesdownlink/uplink (DL/UL) indication types (activation and deactivation),list of secondary carriers (logical carrier indexes), and informationabout a ranging indicator of the activated carrier.

The base station (BS) may set a polling bit of a MAC Control ExtendedHeader (MCEH) of the AAI_CM-CMD message to ‘1’, and transmit theresultant AAI_CM-CMD message. Upon receiving the AAI_CM-CMD message fromthe base station (BS), the mobile station (MS) transmits an AAI messageacknowledgement (AAI_MSG-ACK) message or a Message ACK Extended Header(MAEH) to the base station (BS), such that the mobile station (MS) caninform the base station (BS) of the successful reception of theAAI_CM-CMD message. A detailed description thereof will hereinafter bepresented.

The mobile station (MS) transmits the AAI_CM-IND MAC control message tothe base station (BS) through the primary carrier, such that the basestation (BS) can confirm that the mobile station (MS) has successfullyactivated/deactivated the carriers listed in the AAI_CM-CMD message. Incase of the activation, when DL/UL of a newly activated carrier is readyto be used for data traffic transmission, the mobile station (MS) cantransmit the AAI_CM-IND message.

In the case where the mobile station (MS) acting as a single wirelesstransceiver (also called a single Radio Frequency (RF) transceiver)performs secondary carrier activation when supporting data transmissionthrough both the primary carrier and the secondary carrier, the mobilestation (MS) may reset hardware setup (e.g., RF center frequency). Afterthe completion of hardware reset and synchronization on a new carrier,the mobile station (MS) transmits the AAI_CM-IND message to the basestation (BS) such that it commands the base station (BS) to prepare fora new carrier and resumes communication with the base station (BS).After the base station (BS) receives the AAI_CM-IND MAC message, thebase station (BS) may begin to transmit data on the activated secondarycarrier.

Next, the primary carrier change will hereinafter be described indetail. Differently from general inter-FA (inter-Frequency Area)handover, the primary carrier change may include the change of a servingcarrier of a mobile station (MS) belonging to the multi-carrier basestation (BS) without changing the MAC layer security and the mobilitycontext. The mobile station (MS) recognizing the multi-carrier cansupport the primary carrier change. For the purpose of load balancing,variable carrier channel quality or other factors, the base station (BS)may command the primary carrier change of the mobile station (MS)through the AAI_CM-CMD MAC control message on a current primary carrier,such that the mobile station (MS) primary carrier is changed to one ofthe fully configured carriers allocated to the same base station (BS) bythe AAI_CM-CMD MAC control message. If the mobile station (MS) receivesthe AAI_CM-CMD message in which the polling bit of the MCEH is set to‘1’, the mobile station (MS) may transmit the AAI_MSG-ACK message or theMAEH in response to the AAI_CM-CMD message. The mobile station (MS)severs a control signal on the serving carrier, and then switches to thetarget fully configured carrier at an action time specified by the basestation (BS). The action time defined by the AAI_CM-CMD message may beset to a value that is higher than that of a retransmission timer forthe AAI_CM-CMD message. A detailed description thereof will hereinafterbe presented.

In the case where the mobile station (MS) supports the carrieraggregation mode and a target carrier is one of the MS's activatedsecondary carriers, the mobile station (MS) may receive data and controlsignals on the target carrier immediately after switching. Otherwise,the mobile station (MS) may reconfigure its own hardware (e.g., RFcenter frequency), and may switch to the target carrier. If the rangingindicator of the AAI_CM-CMD message is set to ‘1’, the mobile station(MS) performs periodic ranging to the target carrier. Upon successfulcompletion of periodic ranging, the mobile station (MS) transmits theAAI_CM-IND message to the base station (BS) so as to inform the basestation (BS) of the readiness of the target carrier. Upon receiving theAAI_CM-IND message from the mobile station (MS) through the targetprimary carrier, the base station (BS) may transmit data and controlsignals to the mobile station (MS). In the case where the common MACmanages both the serving primary carrier and the target primary carrier,network re-entry is not requested at the target primary carrier. Thebase station (BS) may command the mobile station (MS) to perform primarycarrier change without scanning. In association with the multi-carriersupported MS, upon completion of the primary carrier change, a logicalcarrier index of the serving primary carrier may be one-to-one exchangedwith that of the target primary carrier.

The mobile station (MS) may perform scanning of other assigned carriersthat do not serve the mobile station (MS) according to an unsolicitedscheme or a base station's indication message. The mobile station (MS)may report the scanning result to the serving base station, and the basestation (BS) may use the report result to decide a carrier that is to beswitched by the mobile station (MS). In this case, assuming that thetarget carrier does not serve the current mobile station (MS), themobile station (MS) may establish synchronization with the targetcarrier.

The AAI_CM-CMD message for the primary carrier change may be transmittedon the primary carrier, and may include information about a targetprimary carrier index, an indication for the next status of the servingprimary carrier, an action time, and a ranging indicator. At this time,if the mobile station (MS) does not support the carrier aggregation, afield denoted by “Next Status of Serving Primary Carrier” may always beset to zero ‘0’. The serving primary carrier may be activated ordeactivated according to the indication for the next status of theserving primary carrier.

MAC Control Message for Carrier Management

The Advanced Air Interface Carrier Management Command (AAI_CM-CMD)message is transmitted by a base station (BS), and the carriermanagement procedure, such as the carrier activation/deactivation or theprimary carrier change, starts operation. In response to the AAI_CM-CMDMAC control message, the mobile station (MS) may transmit the AAI_CM-INDMAC control message.

The base station (BS) may start operating the retransmission timer aftertransmitting the AAI_CM-CMD message. If the base station (BS) receivesan acknowledgement (ACK) message of the AAI_CM-CMD message before theexpiration of the retransmission timer, the base station (BS) may stopoperation of the timer and then perform a procedure corresponding to theaction code. If the base station (BS) does not receive theacknowledgement (ACK) message before the expiration of theretransmission timer, the base station (BS) may retransmit theAAI_CM-CMD message.

In the case where the AAI_CM-CMD message newly activates the targetsecondary carrier or indicates the primary carrier change to thedeactivated target carrier, the mobile station (MS) transmits theAAI_CM-IND message to the base station (BS) such that it may inform thebase station (BS) of the readiness of the target carrier. The AAI_CM-INDmessage may include the action code about either the secondary carriermanagement or the primary carrier change.

Acknowledgement of MAC Control Message in Carrier Management Procedure

In a carrier management procedure, a method for transmittingacknowledgement (ACK) messages related to AAI_CM-CMD and AAI_CM-INDmessages in accordance with one embodiment of the present invention willhereinafter be described in detail.

In a conventional carrier management procedure, the AAI_CM-CMD messagemay be used to indicate either the secondary carrier management or theprimary carrier change. The AAI_CM-IND message may be used to answer theAAI_CM-IND message. However, the AAI_CM-IND message may be used indifferent ways according to indicated actions.

Usages of the AAI_CM-IND message will hereinafter be described withreference to FIGS. 4( a) and 4(b). FIGS. 4( a) and 4(b) are flowchartsillustrating message exchange in response to a carrier managementprocedure. The carrier status can be represented as follows unless thereis no separate description in the annexed drawings of the presentinvention. In the following drawings, a carrier denoted by a solid linemay represent an activated carrier, and a carrier denoted by a bold linemay represent a primary carrier, and a carrier denoted by a dotted linemay represent a deactivated carrier.

Referring to FIG. 4( a), an Advanced Base Station (ABS) transmits anAAI_CM-CMD message indicating secondary carrier management(activation/deactivation) to an Advanced Mobile Station (AMS) at stepS411. The AMS transmits an AAI_CM-IND message to the ABS, such that itinforms the ABS that a target carrier indicated by the AAI_CM-CMDmessage was successfully activated or deactivated. In the case of thesecondary carrier activation shown in FIG. 4( a), the AAI_CM-IND messageis transmitted when DL/UL of the newly activated secondary carrier isready to transmit data traffic at step S412. Because of the AAI_CM-INDmessage transmission, the ABS and the AMS may communicate with eachother even through the target secondary carrier at step S413.

Referring to FIG. 4( b), the ABS transmits the AAI_CM-CMD messageindicating the primary carrier change to the AMS at step S421. In orderto inform the ABS of the successful reception of the AAI_CM-CMD message,the AMS transmits the AAI_CM-IND message to the ABS at step S422. Duringthe action time given by the AAI_CM-CMD message, the primary carrierchange is performed at step S423. Although the exemplary primary carrierchange shown in FIG. 4( b) illustrates that the serving primary carriermaintains an activation status after the completion of the primarycarrier change, the serving primary carrier may enter a deactivationstatus after the completion of the primary carrier change. In addition,if the target carrier is kept in the deactivation status, the AMStransmits a bandwidth request (BR) to the ABS after the target carrierhas been activated, such that it may inform the ABS of the readiness ofthe target carrier.

As described above, the AAI_CM-IND message may be adapted to inform theABS of the readiness of the target carrier when the secondary carriermanagement is indicated by the AAI_CM-CMD message. If the primarycarrier change is indicated by the AAI_CM-CMD message, the AAI_CM-INDmessage may be adapted to inform the ABS that the AAI_CM-CMD message wassuccessfully received in the AMS.

In the case of the secondary carrier management, the ABS is unable toconfirm whether the AMS has received the AAI_CM-CMD message, such thatthe ABS has to wait indefinitely for the AAI_CM-IND message until theAMS has completed the activation of the target carrier. In addition, inthe case of the primary carrier change, the AAI_CM-IND message mayrepresent only the successful reception of the AAI_CM-CMD message, andmay not be used as a message that indicates the readiness of the targetcarrier.

As described above, the obscurity indicating different purposes of theAAI_CM-IND message may be present as necessary, such that the followingfactors may be considered to solve the above obscurity.

Each of the AAI_CM-CMD message and the AAI_CM-IND message corresponds tothe MAC control message. The MAC control message may be used when thepeer-to-peer protocol of each MAC layer of the ABS and the AMS performsa control plane function. The MAC control message may be returned to aMAC Protocol Data Unit (MAC PDU) that is transmitted through broadcast,unicast, or random access connection. There is only one unicast controlconnection, and Hybrid Automatic Repeat reQuest (HARQ) may be operatedin the MAC control message that is transmitted on the unicast controlconnection.

If the MAC PDU includes a payload from the control connection, a MACControl Extended Header (MCEH) may be utilized. The MCEH format may bedefined as shown in Table 2. As can be seen from Table 2, the pollingbit of the MCEH may be set to ‘0’ when the acknowledgement of the MACcontrol message reception is not requested, and may be set to ‘1’ whenthe acknowledgement of the MAC control message reception is requested.

TABLE 2 Size Syntax (bit) Note MCEH ( ) { EC 1 Encryption Contolindicator 0 = Payload is not encrypted 1 = Payload is encrypted ControlConnection 1 Channel ID identify separate Channel ID (CCC ID)fragmentation/reassembly state machines 0: channel 1 1: channel 2 SNIndicator 1 0 = no FC and sequence number 1 = FC and sequence number arefollowed If (SN Indicator = 0) { Reserved 5 For byte alignment else {Polling 1 0 = no acknowledgement required 1 = acknowledge required uponreceiving the MAC message FC 2 Fragmentation control (see Table 665) SN8 Payload sequence number Reserved 2 For byte alignment } }

The ABS and the AMS may use a MAC Control Message ACK Extended Header(MAEH) to indicate the reception of a specific MAC control message thathas already been received. In the case where the ABS or the AMS receiveseither the MAC control message or the MAC control message fragmenthaving an MCEH wherein the polling bit is set to ‘1’, the ABS or the AMStransmits an MAEH as an acknowledgment after receiving a full messagewith the sequence number of a MAC control message PDU or a sequencenumber of the last received fragment if fragmented. The MAEH format canbe represented by the following Table 3.

TABLE 3 Syntax Size (bits) Notes MAEH ( ) { Type 4 MAEH type ACK_SN 8 SNretrieved from the MCEH of the MAC PDU with the Polling bit set to 1Control Connection 1 Control Connection Channel ID Channel ID (CCC ID)(CCC ID) that the MAC management message is received. Reserved VariableFor byte alignment }

In the meantime, the ABS and the AMS may use the AAI messageacknowledgement (AAI_MSG-ACK) message to indicate the reception of theAMC control message. If a message in which the polling bit of the MCEHis set to ‘1’ is received through control connection, the ABS and theAMS may transmit the AAI_MSG-ACK message as an acknowledgement messageindicating MAC control message reception.

In association with the above-mentioned operation in which theAAI_MSG-ACK message or the MAEH is used as an acknowledgement messagewhen the polling bit of the MCEH of the MAC control message is set to‘1’, MAC management reliability will hereinafter be described in detail.

All MAC control messages can be fragmented. As described above, HARQ canbe applied to all kinds of unicast MAC control messages. Aretransmission timer may be defined for a MAC control message thatrequires reliable transmission. The retransmission timer startsoperation when a transmitter starts transmitting the MAC controlmessage, and waits for a response message (e.g., an AAI Ranging Response(AAI_RNG-RSP) message is a response to an AAI ranging request(AAI_RNG-REQ) message. The retransmission timer stops operation uponreceiving a response message from a receiver. In the case where a localNACK for the MAC control message is operated, and the HARQ processresults in a failure before the expiration of the retransmission timer,the transmitter may start retransmitting a full control messagetransmitted from the failed HARQ burst or a control message fragment asnecessary. During the retransmission of the control message fragmentretransmission started by the local NACK, the transmitter may retransmita control message fragment having the same information (MCEH andpayload) as in an initial transmission operation.

The transmitter may ask the receiver to transmit the MAC layeracknowledgement (ACK) message so as to determine a status of thetransmitted control message. If the MAC layer acknowledgement (ACK)message is used, the transmitter may set the polling bit to ‘1’ at theMCEH of the MAC PDU that includes either a full control message or thelast pending fragment of a control message. Immediately aftertransmission of the MAC PDU in which the polling bit is set to ‘1’, thetransmitter starts operating an ACK timer and waits for the AAI_MSG-ACKmessage or the MAEH. In the case of receiving a local NACK for a MAC PDUthat sends back the MCEH in which the polling bit is set to ‘1’, thetransmitter retransmits the MAC PDU having the last fragment and at thesame time sets the polling bit of the MCEH to ‘1’. Upon receiving thelocal NACK, the ACK timer stops operation. The ACK timer stopped by thelocal NACK retransmits the last fragment and at the same time restartsoperation. Upon receiving the AAI_MSG-ACK message or the MAEG, the ACKtimer stops operation. If the ACK timer has expired before the receptionof the ACK message or the expiration of the retransmission timer, thetransmitter may restart retransmission of an overall message. If theretransmission timer has expired, the transmitter may stop operating theACK timer. If the retransmission operation begins after the ACK timer orthe retransmission timer has expired, the transmitter may reset theretransmission timer.

If the receiver receives a control message of the MAC PDU in which thepolling bit of the MAEH is set to ‘1’ or a control message fragment, thereceiver may answer the MAC PDU control message or the control messagefragment using the AAI_MSG-ACK message or the MAEH so as to indicate thereception of the full control message. In relation to the fragmentedcontrol message, the receiver receives all fragments of the controlmessage, and then transmits the AAI_MSG-ACK message or the MAEH.

A general transmission scheme for the MAC control message willhereinafter be described in detail.

First of all, various types of request/response (REQ/RSP) messages willhereinafter be described. For example, AAI ranging request/AAI rangingresponse (AAI_RNG-REQ/AAI_RNG-RSP) messages, AAI Subscriber stationBasic Capability Request/AAI Subscriber station Basic CapabilityResponse (AAI_SBC-REQ/AAI_SBC-RSP) messages, AAI registrationrequest/AAI registration response (AAI_REG-REQ/AAI_REG-RSP) messages,and AAI Handover Request/AAI Handover Response (AAI_HO-REQ/AAI_HO-RSP)messages may be defined as REQ/RSP messages. As described above, in thecase where an REQ MAC control message and its associated RSP message aredefined, a retransmission timer for receiving the RSP message when theREQ message is transmitted may be configured as described in theabove-mentioned control message reliability. If the transmitter receivesno RSP message from the receiver, the transmitter determinestransmission failure of the REQ message such that it can retransmit theREQ message. In other words, assuming that both the REQ message and theRSP message are defined, the RSP message performs a message ACK functionfor reliable transmission of the REQ message.

On the other hand, the RSP message may also answer the REQ message usingthe AAI_MSG-ACK or the MAEH. For example, an AAI handover command(AAI_HO-CMD) message or an AAI handover indication (AAI_HO-IND) messagefor HO cancellation may be defined. Although the AAI_HO-CMD orAAI_HO-IND message may trigger or request a certain procedure oroperation, an RSP message corresponding to the AAI_HO-CMD or AAI_HO-INDmessage has not yet been defined. Therefore, an RSP message is neededfor reliable transmission of the REQ MAC control message. In associationwith the above-mentioned operation, assuming that the polling bit of theMCEH of the REQ MAC control message is set to ‘1’ and the receiversucceeds in receiving the REQ message, the receiver may transmit theAAI_MSG-ACK or MAEH.

In the case of considering the above-mentioned descriptions, theAAI_CM-CMD message serves as a MAC control message in a carriermanagement procedure such that reliable transmission of the AAI_CM-CMDmessage is needed. However, in the currently-defined secondary carriermanagement procedure, the AAI_CM-IND message is transmitted to the ABSafter the activation of a target carrier, such that the ABS is unable torecognize whether the AAI_CM-CMD message was successfully received inthe AMS. Therefore, the embodiment of the present invention proposes animproved technology in which the AAI_CM-CMD message requests a responsemessage (AAI_MSG-ACK message or MAEH) indicating the successfulreception and the AAI_CM-IND message is adapted to inform the ABS of thereadiness of the target carrier.

In addition, assuming that the target carrier (T-carrier) is one ofdeactivated carriers in a primary carrier change procedure, according tothe currently defined procedure, the AMS has transmitted a bandwidthrequest (BR) to the ABS so as to inform the ABS of the readiness of thetarget carrier (T-carrier), and the AAI_CM-IND message has been usedonly to acknowledge the successful reception of the AAI_CM-CMD message.The above-mentioned AAI_CM-IND message has an objective different fromthat of another AAI_CM-IND message that has been defined in thesecondary carrier management procedure, resulting in the occurrence ofthe obscurity. In order to remove the obscurity, not only in the primarycarrier change procedure but also in the secondary carrier managementprocedure, it is preferable that the AAI_CM-IND message be used as amessage that informs the ABS of the readiness of the target carrier(T-carrier).

Therefore, three-step procedures of the AAI_CM-CMD message, theacknowledgement (ACK) message of the AAI_MSG-ACK message or the MAEH,and the AAI_CM-IND message can be defined as follows.

The ABS sets a polling bit of the MCEH of the AAI_CM-CMD message to ‘1’,and transmits the resultant AAI_CM-CMD message to the ABS. The ABSstarts operating the retransmission timer when transmitting theAAI_CM-CMD message. If the ABS receives the AAI_MSG-ACK message or theMAEH before the expiration of the retransmission timer, the ABS stopsoperating the retransmission timer and begins to perform a correspondingcarrier management procedure. If the retransmission timer has expired,the ABS may retransmit the AAI_CM-CMD message.

From the viewpoint of the AMS, if the AMS has successfully received theAAI_CM-CMD message, the AMS may transmit the AAI_MSG-ACK message or MAEHto inform the ABS of the successful reception of the AAI_CM-CMD message.

The AAI_CM-IND message may be adapted to inform the ABS of the readinessof the target carrier (T-carrier), irrespective of action codes (where,a code ‘0’ means secondary carrier management and a code ‘1’ meansprimary carrier change) of the AAI_CM-CMD message. That is, if a targetcarrier (T-carrier) of the AAI_CM-CMD message is one of the deactivatedcarriers (wherein the target carrier may be a deactivated carrier whenthe AMS is operated in single carrier mode), the AAI_CM-IND message maybe used to inform the ABS of the readiness of the target carrier(T-carrier).

In association with the above-mentioned description, if the action codeof the AAI_CM-CMD message indicates the primary carrier change, theAAI_CM-IND message may be transmitted on the target carrier (T-carrier)after successfully performing the switching to the target carrier(T-carrier) at an action time specified by the AAI_CM-CMD message. Ifthe AMS fails to perform the switching at the action time, theAAI_CM-IND message may be transmitted on the serving primary carrier. Ifthe serving carrier (S-carrier) is deactivated, the AAI_CM-IND messagemay also be transmitted to the serving carrier (S-carrier) through abandwidth request (BR).

Secondary carrier management according to one embodiment of the presentinvention will hereinafter be described with reference to FIG. 5. FIG. 5is a flowchart illustrating usages of an acknowledgement message for usein a secondary carrier management procedure according to one embodimentof the present invention. Referring to FIG. 5, the AAI_CM-CMD message inwhich the action code indicates the secondary carrier management istransmitted from the ABS to the AMS, the activation of the targetcarrier (T-carrier) is indicated by an indication type of the AAI_CM-CMDmessage at step S501. A target carrier (T-carrier) may be represented bya deactivated carrier denoted by a dotted line. When the ABS transmitsthe AAI_CM-CMD message, the polling bit of the MCEH may be set to ‘1’,such that the resultant AAI_CM-CMD message is then transmitted.Therefore, the AAI_MSG-ACK message or the MAEH in relation to theAAI_CM-CMD message may be transmitted through the primary carrier(P-carrier) at step S502. If the ABS receives the AAI_MSG-ACK message orthe MAEH from the AMS, it waits for the AAI_CM-IND message. The AMSrepresents the target carrier (T-carrier) by an activated carrierdenoted by a solid line, and transmits the AAI_CM-IND message indicatingthe readiness of the target carrier (T-carrier) through the primarycarrier (P-carrier) at step S503. After the transmission of theAAI_CM-IND message, the ABS and the AMS may communicate with each otherthrough the target carrier (T-carrier).

An exemplary form of primary carrier change according to one embodimentof the present invention will hereinafter be described with reference toFIGS. 6( a) and 6(b). FIGS. 6( a) and 6(b) are flowcharts illustratingusages of an acknowledgement message for use in a primary carrier changeprocedure according to one embodiment of the present invention.

An exemplary case in which a target primary carrier is a deactivatedcarrier will hereinafter be described with reference to FIG. 6( a).Referring to FIG. 6( a), the AAI_CM-CMD message in which the action codeindicates primary carrier change is transmitted from the ABS to the AMSat step S611. The ABS may set the polling bit of the MCEH of theAAI_CM-CMD message to ‘1’ so as to acknowledge successful reception ofthe AAI_CM-CMD message. The AMS may transmit the AAI_MSG-ACK message orMAEH for the AAI_CM-CMD message through the serving carrier (S-carrier)at step S612. The AAI_MSG-ACK message or the MAEH may be transmitted tothe ABS prior to the action time specified by the AAI_CM-CMD message.The AMS performs switching to the target carrier (T-carrier) at anaction time by referring to the action time specified by the AAI_CM-CMDmessage. If necessary, the synchronization and the CDMA ranging (orperiodic ranging) may be performed through the target carrier(T-carrier) at step S613. Because the target carrier (T-carrier) is adeactivated carrier, the AMS may transmit the AAI_CM-IND messageindicating readiness of the target carrier (T-carrier) to the ABSthrough the target carrier (T-carrier) after the lapse of the actiontime at step S614. After the execution of the primary carrier change,the ABS may transmit and receive control signals and data to and fromthe AMS through the target primary carrier.

In this case, the AAI_CM-IND message may be transmitted through thechanged target primary carrier after the completion of the successfulprimary carrier change. In contrast, if the primary carrier changeresults in a failure, the AAI_CM-IND message may be transmitted throughthe serving primary carrier. Although FIG. 6( a) shows that the servingcarrier (S-carrier) is activated after the completion of the primarycarrier change, the ‘Next State of Serving Primary Carrier’ field of theserving primary carrier contained in the AAI_CM-CMD message maydetermine whether the serving primary carrier is to be maintained in anactivated or deactivated state after the completion of the primarycarrier change. If the AMS is a single carrier AMS that does not supportcarrier aggregation, the above-mentioned field may always be set to ‘0’(where the serving carrier (S-carrier) is deactivated after thecompletion of the primary carrier change). If the serving primarycarrier is deactivated after the completion of the primary carrierchange and then the primary carrier change results in a failure, theAAI_CM-IND message may be transmitted through a bandwidth request (BR)on the serving carrier (S-carrier).

Next, an exemplary case in which the target primary carrier is anactivated carrier will hereinafter be described with reference to FIG.6( b). The transmission of the AAI_CM-CMD message transmission (S621)and the transmission of the AAI_MSG-ACK message or MAEH (S622) shown inFIG. 6( b) are similar to those of FIG. 6( a). In FIG. 6( b), becausethe target carrier (T-carrier) is a pre-activated carrier, theAAI_CM-IND message that informs the ABS of the readiness of the targetcarrier (T-carrier) may be omitted. In other words, the AMS does nottransmit the AAI_CM-IND message, and may transmit and receive controlsignals and data to and from the ABS through the target primary carrierat an action time specified by the AAI_CM-CMD message. The servingprimary carrier may also be deactivated after the completion of thecarrier change.

Action Time and Disconnection Time in Carrier Management Procedure

One embodiment in which an action time specified by the AAI_CM-CMDmessage is defined in the carrier management procedure and adisconnection time of a deactivated carrier is defined will hereinafterbe described in detail.

The primary carrier change for use in the carrier management procedurestarts operation by the AAI_CM-CMD message. The AAI_CM-CMD message is aMAC control message that requests reliable transmission, and the ABStransmits the AAI_CM-CMD message and starts operating the retransmissiontimer. In addition, the action time field is defined in the AAI_CM-CMDmessage, and the AMS performs switching to the target fully configuredcarrier at an action time specified by the AAI_CM-CMD message. Theaction time may be defined as a Least Significant Bit (LSB) of a superframe number (SFN) at a time that switches to the target carrier(T-carrier).

By the currently defined action time, the action time may expire whilethe AMS receives the AAI_CM-CMD message and prepares for the operationof T-carrier activation. In other words, although the AMS is normallyoperated, the target carrier (T-carrier) may not yet be prepared for atan action time where the primary carrier change is to be carried out. Inother words, when the action time specified by the AAI_CM-CMD message isset to a specific time before the AAI_CM-IND message is received by inthe ABS, the ABS may misunderstand that the AAI_CM-CMD message has notbeen successfully received in the AMS and the AMS has rejected therequest of the ABS. This misunderstanding may cause primary carrierchange to fail.

Therefore, if necessary, the action time may be established at aspecific time after the lapse of the retransmission timer expirationtime of the AAI_CM-CMD message. In other words, the action time may bedenoted by (Action Time≧AAI_CM-CMD Transmission TimingPoint+Retransmission Timer Value). By the newly defined action time, theABS may determine that the AMS has not received the AAI_CM-CMD messageat the expiration time of the retransmission timer such that it canretransmit a new AAI_CM-CMD message in which the action time is newlyspecified. Accordingly, although the primary carrier change action timeis properly established, and the AMS normally receives the message andis operated as described above, the misunderstanding of the ABS thatdecides that the primary carrier change procedure has failed can beprevented.

The action time field of the above-mentioned AAI_CM-CMD message may bedefined as shown in the following Table 4.

TABLE 4 Action Time 3 LSB bits of Superframe number at the time toswitch to the target carrier This value shall be set to the value morethan the retransmission timer for AAI_CM-CMD message

In addition, it is necessary to concretely define the disconnection timein the primary carrier change procedure. The serving primary carrier maybe deactivated after the completion of the primary carrier changeaccording to indication information of the AAI_CM-CMD message.Information about when the serving primary carrier is to be deactivatedis not defined in a conventional carrier change procedure. Therefore,one example in which the AMS transmits the AAI_CM-IND message and at thesame time disconnects a control path from the serving carrier(S-carrier) is not excluded. In this case, since a current time does notyet reach the action time and the target carrier (T-carrier) is not setto the primary carrier, a control message may be lost in the range fromthe disconnection time of the serving carrier (S-carrier) to the actiontime. In the primary carrier change, the disconnection time of theserving carrier (S-carrier) is defined to be identical to the actiontime defined by the AAI_CM-CMD message, such that control message lossis prevented.

FIG. 7 is a conceptual diagram illustrating the relationship between anaction time and a retransmission timer for use in a primary carrierchange procedure according to one embodiment of the present invention.Referring to FIG. 7, the ABS transmits the AAI_CM-CMD message to the AMSand at the same time starts operating the retransmission timer at stepS701. The action code of the AAI_CM-CMD message may represent theprimary carrier change, and the action time of the primary carrierchange may be specified by the ‘Action Time’ field. In addition, the‘Next State of Serving Primary Carrier’ field of the AAI_CM-CMD messagemay indicate that the serving primary carrier (S-PC) is deactivatedafter the primary carrier change. The AMS receives the AAI_CM-CMDmessage from the ABS. In response to the AAI_CM-CMD message, the AMS maytransmit the AAI_CM-IND message indicating the readiness (activation) ofthe target carrier (T-carrier) to the ABS at step S702. After the targetcarrier (T-carrier) is activated in response to the AAI_CM-IND message,until a current time reaches the action time at which the switching tothe target carrier (T-carrier) is performed, a control message can stillbe transmitted and received through the serving primary carrier (S-PC),and data other than the control message can be communicated through thetarget carrier (T-carrier). Therefore, the control message may not belost until the serving primary carrier is severed. As described above,the action time (S704) specified by the AAI_CM-CMD message may be set toa time later than the retransmission timer expiration time (S703). TheAMS may transmit and receive data and control messages to and from theABS through a target primary carrier at the action time (S704). Thedisconnection of control signal communication through the servingprimary carrier (S-PC) at a disconnection time, and the disconnectiontime may be defined to be identical to the action time. Since the nextstatus of the primary carrier (P-carrier) is indicated as a deactivationstatus, the serving primary carrier (S-PC) can be deactivated after theaction time (disconnection time). In the meantime, in the case where thenext status of the serving primary carrier (S-PC) is commanded to bekept in an activation status after the completion of the primary carrierchange, only control signal communication through the serving primarycarrier (S-PC) is interrupted and the serving primary carrier (S-PC) canbe kept in an activation status.

On the other hand, in the secondary carrier management(activation/deactivation), the ABS receives the AAI_CM-IND MAC controlmessage from the AMS through the primary carrier (P-carrier), such thatthe ABS can confirm that carriers listed in the AAI_CM-CMD message weresuccessfully activated or deactivated. In the case of activating thecarriers listed in the AAI_CM-CMD message, the AMS can transmit theAAI_CM-IND message when downlink/uplink (DL/UL) of the newly activatedcarrier is ready to be used for data traffic transmission.

In relation to the above description, the AMS can be operated in acarrier aggregation mode in which the AMS can simultaneously transmitand receive data to and from the ABS through one or more carriers.Although the AMS supporting the carrier aggregation mode receives nassigned carriers from the ABS, the AMS having only the capabilitycapable of aggregating only m carriers (1<m<n, m=integer) from among then assigned carriers may be present. In the case where all the m carriersare used as activated carriers by the AMS, a certain activated secondarycarrier (Carrier_1) may be deactivated due to a channel quality, loadbalancing, or the like, and the activation of another one (Carrier_2)from among the n assigned carriers may be needed.

In the above-mentioned case, a secondary carrier management actioncorresponding to the action code ‘0’ may be specified in the currentlydefined AAI_CM-CMD message, such that a first target carrier (TargetCarrier_1) can be deactivated and at the same time a second targetcarrier (Target Carrier_2) can be activated.

The AMS may transmit the AAI_CM-IND message in response to oneAAI_CM-CMD message. The AAI_CM-IND message has the following meaningsaccording to actions indicated by the AAI_CM-CMD message. If the actionindicated by the AAI_CM-CMD message is activation, the AAI_CM-INDmessage is transmitted from the AMS to the ABS so as to indicate thatthe target carrier (T-carrier) was activated and the readiness of datacommunication was completed. Otherwise, if the action indicated by theAAI_CM-CMD message is deactivation, the AMS transmits the AAI_CM-INDmessage to the ABS and at the same time data communication with thetarget carrier is severed.

Therefore, if one target carrier (Target Carrier_2) indicated to beactivated and the other target carrier (Target Carrier_1) indicated tobe deactivated cannot be simultaneously activated due to the restrictionof the above-mentioned AMS capability, the AMS is unable to transmit theAAI_CM-IND message indicating the readiness of the newly activatedtarget carrier (Target Carrier_2) to the ABS. In other words, the AMScan activate the target carrier (Target Carrier_2) after the completionof deactivation of the other target carrier (Target Carrier_1), and nomethod capable of informing the ABS of the activation of the targetcarrier (Target Carrier_2) using the AAI_CM-IND message is defined inthe currently defined AAI_CM-IND message.

In order to solve the above-mentioned problem, a carrier disconnectiontime may be defined in relation to secondary carrier management(activation/deactivation). When the ABS transmits the AAI_CM-CMD messageto command the deactivation of the target carrier, a disconnection timeof the target carrier can be defined in relation to the AAI_CM-CMDmessage. A variety of methods (a), (b), (c) and (d) for defining thecarrier disconnection time will hereinafter be described.

-   -   (a) In the case where the action code of the AAI_CM-CMD message        is set to ‘0’ (secondary carrier management) and the indication        type #1 is set to ‘1’ (deactivation), a disconnection time is        defined.    -   (b) Only when the action code of the AAI_CM-CMD message is set        to ‘0’ (secondary carrier management), the indication type #0 is        set to ‘1’ (activation), and the indication type #1 is also set        to ‘1’ (deactivation), a disconnection time is defined.    -   (c) Only when a disconnection time flag is defined and the        disconnection time flag is set to ‘1’, a disconnection time is        defined.    -   (d) No disconnection time is defined in the AAI_CM-CMD message,        and a reception time of the AAI_CM-CMD message is implicitly        defined as a disconnection time of the target carrier.

In the case where the number of target carriers to be deactivated in theabove-mentioned cases (a) and (b) is set to ‘n’, n disconnection timesfor individual carriers may be defined, and the same one disconnectiontime may be defined for all the n target carriers. In theabove-mentioned method (c), the disconnection time flag may be set to‘1’ only when an unexpected problem caused by the above-mentioned AMScapability occurs (i.e., only when the first target carrier (TargetCarrier_1) and the second target carrier (Target Carrier_2) cannot besimultaneously activated).

FIG. 8 illustrates a disconnection time for use in a secondary carriermanagement procedure according to one embodiment of the presentinvention. A secondary carrier management procedure to be used when adisconnection time is defined will hereinafter be described withreference to FIG. 8. Referring to FIG. 8, the AMS transmits and receivesa control message and data to and from the ABS through a primary carrier(PC) at step S801. The AMS transmits and receives data to and from theABS through a secondary carrier (T-SC_1) at step S802. The AAI_CM-CMDmessage transmitted from the AMS to the AMS includes parameters that areneeded to deactivate the first target secondary carrier (T-SC_1) andactivate the second target secondary carrier (T-SC_2). In addition, theAAI_CM-CMD message includes a disconnection time for the first targetsecondary carrier (T-SC_1) at step S803. As described above, the firsttarget secondary carrier (T-SC_1) and the second target secondarycarrier (T-SC_2) cannot be simultaneously activated due to therestriction of the AMS capability, such that the AMS firstly deactivatesthe first target secondary carrier (T-SC_1) at the disconnection timeindicated by the AAI_CM-CMD message at step S804. As can be seen fromFIG. 8, the representation of the first target secondary carrier(T-SC_1) is changed from a solid line (activation) to a dotted line(deactivation) at the disconnection time. By the deactivation of thefirst target secondary carrier (T-SC_1), the AMS can activate the secondtarget secondary carrier (T-SC_2). The AMS deactivates the deactivatedsecond target secondary carrier (T-SC_2) on the basis of the AAI_CM-CMDmessage. If data is ready to be transmitted or received through thenewly activated second target carrier (T-SC_2), the AMS informs the ABSof the readiness of data at step S805. If the ABS receives theAAI_CM-IND message from the AMS, data can be transmitted and/or receivedbetween the ABS and the AMS through the second target secondary carrier(T-SC_2) at step S806. During the above-mentioned secondary carriermanagement procedure, the AMS can continuously transmit and receive acontrol signal and data to and from the ABS through the primary carrier(PC).

As described above, in reference to the AAI_CM-CMD message forindicating secondary carrier activation and deactivation, as to thedeactivation of the first target secondary carrier, the ABS canrecognize the deactivation of the target carrier at a defineddisconnection time without receiving a message for indicating the firsttarget secondary carrier deactivation from the AMS through theAAI_CM-IND message and others. As to the activation of the second targetsecondary carrier, the ABS receives the AAI_CM-IND message, such that itcan recognize that the second target secondary carrier (T-SC_2) is readyor prepared.

On the other hand, each inventive embodiment for defining thedisconnection time in the secondary carrier management procedure is notlimited only to a specific case in which several target secondarycarriers are unable to be simultaneously activated owing to therestriction of AMS capability, and may also be applied to otherexemplary cases as necessary. Since the disconnection time is defined inan arbitrary case in which the deactivation of the target secondarycarrier (T-SC) is indicated in the secondary carrier managementprocedure, those skilled in the art can easily appreciate that the errorencountered in the secondary carrier management procedure is preventedand the accuracy of operation is increased.

A variety of associated embodiments in which the disconnection time ofthe target secondary carrier is defined by defining a parameter of theAAI_CM-CMD message will hereinafter be described. First of all, basicparameters of the AAI_CM-CMD message can be configured as represented bythe following Table 5.

TABLE 5 Size Field (bit) Description AAI_Carrier Management Commandmessage format( ){ Management Message Type 8 AAI_CM-CMD Action code 1 0:Secondary Carrier Management 1: Primary carrier change If (Action code== 0){ This message is for secondary carrier activation and/ordeactivation Indication Type 2 For Activation and/or Deactivation Bit#0: ‘0’: No action, ‘1’: Activation Bit #1: ‘0’: No action, ‘1’:Deactivation If (Indication Type #0 == 1) Num of target carrier [TBD]The number of newly activated carrier(s) For(i=0; i< Num of targetcarrier; i++){ Target carrier index [TBD] Target carrier index foractivation Activation of DL/UL 1 ‘0’: Both DL/UL are activated ‘1’: DLis activated but UL is not activated Ranging indicator 1 Rangingindicator for target carrier ‘0’: No ranging is required for the targetcarrier ‘1’: Periodic ranging is required for the target carrier } } If(Indication Type #1 == 1){ Num of target carrier [TBD] The number ofdeactivated carrier(s) For(i=0; i< Num of target carrier; i++){ Targetcarrier index [TBD] Target carrier index for deactivation Deactivationof DL/UL 1 ‘0’: Both DL/UL are deactivated ‘1’: UL is deactivated but DLis kept active } } } If (Action code == 1){ This message is for primarycarrier change. Target carrier index [TBD] Target carrier index forprimary carrier change Action Time [TBD] LSB bits of Superframe numberat the time to switch to the target carrier This value shall be set tothe value more than the retransmission time for AAI_CM-CMD message Nextstate of serving primary carrier 1 ‘0’: Serving carrier will bedeactivated after primary carrier change ‘1’: Serving carrier is keptactive after primary carrier change } }

(1) In relation to an indication for target secondary carrier (T-SC)deactivation, a disconnection time can be defined. One disconnectiontime may be defined for N target secondary carriers (N T-SCs).Therefore, some parameters of the AAI_CM-CMD message can be defined asin the following Table 6.

TABLE 6 Size Field (bit) Description ... If (Indication Type #1 == 1){ Num of target carrier [TBD] The number of deactivated carrier(s)Disconnection time [TBD] LSB bits of Superframe number at the time todisconnect the connection with the target carrier(s) For(i=0; i< Num oftarget carrier; i++){    Target carrier index [TBD] Target carrier indexfor deactivation    Deactivation of DL/UL 1 ‘0’: Both DL/UL aredeactivated ‘1’: UL is deactivated but DL is kept active   }  } ...

(2) In relation to an indication for target secondary carrier (T-SC)deactivation, a disconnection time can be defined only when adisconnection time flag is set to ‘1’. One disconnection time may bedefined for N target secondary carriers (N T-SCs). Therefore, someparameters of the AAI_CM-CMD message can be defined as in the followingTable 7.

TABLE 7 Size Field (bit) Description ... If (Indication Type #1 == 1){ Num of target carrier [TBD] The number of deactivated carrier(s)Disconnection time Flag 1 Flag for the disconnection time  If(Disconnection time Flag==1){    Disconnection time [TBD] LSB bits ofSuperframe number at the time to disconnect the connection with thetarget carrier(s)  } For(i=0; i< Num of target carrier; i++){    Targetcarrier index [TBD] Target carrier index for deactivation   Deactivation of DL/UL 1 ‘0’: Both DL/UL are deactivated ‘1’: UL isdeactivated but DL is kept active  }  } ...

(3) In relation to an indication for target secondary carrier (T-SC)deactivation, a disconnection time can be defined. N disconnection timesmay be defined for N target secondary carriers (N T-SCs). Therefore,some parameters of the AAI_CM-CMD message can be defined as in thefollowing Table 8.

TABLE 8 Size Field (bit) Description ... If (Indication Type #1 == 1){ Num of target carrier [TBD] The number of deactivated carrier(s)For(i=0; i< Num of target carrier; i++){    Target carrier index [TBD]Target carrier index for deactivation    Deactivation of DL/UL 1 ‘0’:Both DL/UL are deactivated ‘1’: UL is deactivated but DL is kept active   Disconnection time [TBD] LSB bits of Superframe number at the time todisconnect the connection with the target carrier(s)  }  } ...

(4) In relation to an indication for target secondary carrier (T-SC)deactivation, a disconnection time can be indicated only when adisconnection time flag is set to ‘1’. One or more disconnection timesmay be defined for N target secondary carriers (N T-SCs). Therefore,some parameters of the AAI_CM-CMD message can be defined as in thefollowing Table 9.

TABLE 9 Size Field (bit) Description ... If (Indication Type #1 == 1){ Num of target carrier [TBD] The number of deactivated carrier(s)For(i=0; i< Num of target carrier; i++){    Target carrier index [TBD]Target carrier index for deactivation    Deactivation of DL/UL 1 ‘0’:Both DL/UL are deactivated ‘1’: UL is deactivated but DL is kept active   Disconnection time Flag 1 Flag for the disconnection time    If(Disconnection time Flag==1){      Disconnection time [TBD] LSB bits ofSuperframe number at the time to disconnect the connection with thetarget carrier(s)    }   }  } ...

(5) In the case where activation and deactivation of a target secondarycarrier are simultaneously indicated, a disconnection time can bedefined. One disconnection time may be defined for N target secondarycarriers (N T-SCs). Therefore, some parameters of the AAI_CM-CMD messagecan be defined as in the following Table 10.

TABLE 10 Size Field (bit) Description ... If (Indication Type #1 == 1){ Num of target carrier [TBD] The number of deactivated carrier(s) If(Indication Type #0 = 1){  Disconnection time [TBD] LSB bits ofSuperframe number at the time to disconnect the connection with thetarget carrier(s) } For(i=0; i< Num of target carrier; i++){    Targetcarrier index [TBD] Target carrier index for deactivation   Deactivation of DL/UL 1 ‘0’: Both DL/UL are deactivated ‘1’: UL isdeactivated but DL is kept active   }  } ...

(6) In the case where activation and deactivation of a target secondarycarrier are simultaneously indicated, a disconnection time can bedefined only when a disconnection time flag is set to ‘1’. Onedisconnection time may be defined for N target secondary carriers (NT-SCs). Therefore, some parameters of the AAI_CM-CMD message can bedefined as in the following Table 11.

TABLE 11 Size Field (bit) Description ... If (Indication Type #1 == 1){ Num of target carrier [TBD] The number of deactivated carrier(s)Disconnection time Flag 1 Flag for the disconnection time If (IndicationType #0 == 1 && Disconnection time Flag ==1){  Disconnection time [TBD]LSB bits of Superframe number at the time to disconnect the connectionwith the target carrier(s) } For(i=0; i< Num of target carrier; i++){   Target carrier index [TBD] Target carrier index for deactivation   Deactivation of DL/UL 1 ‘0’: Both DL/UL are deactivated ‘1’: UL isdeactivated but DL is kept active   }  } ...

(7) In the case where activation and deactivation of a target secondarycarrier are simultaneously indicated, a disconnection time can bedefined only when a disconnection time flag is set to ‘1’. One or moredisconnection times may be defined for N target secondary carriers (NT-SCs). Therefore, some parameters of the AAI_CM-CMD message can bedefined as in the following Table 12.

TABLE 12 Size Field (bit) Description ... If (Indication Type #1 == 1){ Num of target carrier [TBD] The number of deactivated carrier(s)For(i=0; i< Num of target carrier; i++){    Target carrier index [TBD]Target carrier index for deactivation    Deactivation of DL/UL 1 ‘0’:Both DL/UL are deactivated ‘1’: UL is deactivated but DL is kept active   Disconnection time Flag 1 Flag for the disconnection time    If(Indication Type #0 == 1 &&     Disconnection time Flag ==1){      Disconnection time [TBD] LSB bits of Superframe number at the timeto disconnect the connection with the target carrier(s)    }   }  } ...

Since the disconnection time of the secondary carrier deactivation isestablished as described in the above embodiments, although amulti-carrier AMS receives indication information of secondary carrieractivation/deactivation through one AAI_CM-CMD message, the confusion ofthe usage of the AAI_CM-IND message is removed, such that the carriermanagement procedure can be effectively and correctly carried out.

Common MAC Handover (HO) and Carrier Change Procedure

As previously stated in FIG. 2( a), in the ABS capable of supporting asingle carrier, one PHY is controlled by one MAC controller, and aplurality of MAC-PHY entities may be present in one cell. One basestation identifier (BSID) is assigned to each MAC-PHY entity. While thesingle carrier supported AMS transmits and receives data by a singleMAC-PHY entity, it may perform inter-frequency handover to anotherMAC-PHY entity having a different BSID in the same cell according to achannel status or other conditions.

In order to perform effective handover, the ABS may periodicallybroadcast a neighbor advertisement (MOB_NBR-ADV) message. TheMOB_NBR-ADV message is configured to transmit only values of differencesin system information (SI) and physical channel information between acurrent serving ABS and each neighbor ABS. In the case of co-locatedFrequency Assignment (FA), a preamble index, handover processoptimization, Downlink Channel Descriptor (DCD)/Uplink ChannelDescriptor (UCD) configuration change count, Type-Length-Value (TLV)coded neighbor information, and the like may be omitted as necessary.

A general handover procedure will hereinafter be described. In the caseof a handover (HO) initiated by an ABS, an unsolicited Advanced AirInterface (AAI) handover command (AAI_HO-CMD) message may be transmittedwithout transmission of an AAI handover request (AAI_HO-REQ) message.The AMS may perform network re-entry to a target ABS at an action timedefined by the AAI_HO-CMD message. If possible, an AAI handoverindication (AAI_HO-IND) message may be transmitted prior to thedisconnection time in response to the AAI_HO-CMD message, however itshould be noted that the transmission of the AAI_HO-IND message isoptional.

General handover (HO) procedures will hereinafter be described withreference to FIGS. 9( a) to 9(c).

FIG. 9( a) shows a hard handover (HO) procedure. Referring to FIG. 9(a), according to either a handover request (AAI_MSHO-REQ) message (S911)received from the AMS or an unsolicited scheme, the serving ABS (S-ABS)transmits a handover command (AAI_BSHO-CMD) message to the AMS at stepS912. In response to the AAI_BSHO-CMD message, the AMS may transmit theAAI_HO-IND message to the serving ABS (S-ABS) at step S913. The AMSperforms a network re-entry procedure to a target ABS (T-ABS) at anaction time specified by the AAI_BSHO-CMD message at step S915. In thehard handover (HO) procedure, the AMS may sever the connection to theserving ABS (S-ABS) before performing the network re-entry procedure(S915) to the target ABS (T-ABS) at step S914. After the completion ofthe network re-entry procedure, the AMS may exchange data traffic withthe target ABS (T-ABS) at step S916.

FIG. 9( b) shows a seamless handover (HO) procedure. The seamlesshandover (HO) means a specific handover in which a Quality of Service(QoS) provided before the execution of handover (HO) is maintainedwithout any change and at the same time that a necessary handover (HO)is performed. According to either a handover request (AAI_MSHO-REQ)message (S921) received from the AMS or the unsolicited scheme, theserving ABS (S-ABS) may transmit a handover command (AAI_BSHO-CMD)message to the AMS at step S922. In response to the AAI_BSHO-CMDmessage, the AMS may transmit the AAI_HO-IND message to the serving ABS(S-ABS) at step S923. The AMS may sever the connection to the servingABS (S-ABS) at a disconnection time at step S924. The AMS may exchangeranging request (RNG-REQ)/ranging response (RNG-RSP) messages with thetarget ABS (T-ABS) at an action time specified by the AAI-BSHO-CMDmessage at step S925, and may exchange traffic with the target ABS(T-ABS) at step S926.

FIG. 9( c) shows an Establish Before Break (EBB) handover (HO)procedure. According to either a handover request (AAI_MSHO-REQ) message(S931) received from the AMS or an unsolicited scheme, the serving ABS(S-ABS) transmits a handover command (AAI_BSHO-CMD) message to the AMSat step S932. In response to the AAI_BSHO-CMD message, the AMS maytransmit a handover indication (AAI_HO-IND) message to the serving ABS(S-ABS) at step S933. The AMS performs network re-entry to the targetABS (T-ABS) at an action time defined by the AAI_BSHO-CMD message, andat the same time continuously communicates with the serving ABS (S-ABS)at step S934. Upon completion of the network re-entry to the target ABS(T-ABS), the AMS may be disconnected from the serving ABS (S-ABS) at adisconnection time at step S935. After the completion of the networkre-entry procedure, the AMS may exchange data traffic with the targetABS (T-ABS) at step S936.

On the other hand, if the AMS supports multiple carriers as previouslystated in FIG. 2( b), a plurality of FAs (carriers) may be controlled bya single common MAC. If the plurality of FAs (carriers) is controlled bya single common MAC, a single Base Station Identifier (BSID) may beassigned to a plurality of frequency channels. In relation to the abovedescription, there may be considered an exemplary case in which a singlecarrier supported AMS (i.e., an AMS capable of exchanging data with anABS by a single MAC-PHY entity during an arbitrary TTI) receives anecessary service through one of carriers controlled by a common MACsuch that it may be necessary for the single carrier supported AMS toperform handover (HO) to another carrier controlled by the common MACdue to variation in load balancing or channel quality. The handover (HO)of the single carrier supported AMS may also be carried out through thesame procedure as in the above-mentioned inter-frequency handover (HO).However, one embodiment of the present invention proposes a simplerhandover scheme on the basis of the fact that handover (HO) of thesingle carrier supported AMS is an inter-carrier handover (HO)controlled by a common MAC, such that the exchange of unnecessaryinformation (e.g., a network re-entry procedure) is omitted in a similarmanner to a primary carrier change performed by the multi-carriersupported AMS.

In a single carrier supported AMS operated in the conventionalmulti-carrier system, a handover (HO) procedure in which networkre-entry is omitted is not yet defined. Therefore, when all the singlecarrier supported AMSs perform handover (HO), the single carriersupported AMSs must perform a minimum number of network re-entryprocedures (e.g., the exchange of RNG-REQ/RSP messages) at an actiontime indicated by the AAI_HO-CMD message. However, as defined in theprimary carrier change of the multi-carrier (MC) operation, a processsuch as a network re-entry process may be omitted from handover (HO)between common MAC carriers of the single carrier supported AMS. All thecarriers controlled by the common MAC are controlled by a single ABS,such that a value such as a station identifier (STID) need not beallocated during the inter-carrier handover (HO), and other proceduressuch as authentication and the like may be omitted. Therefore, efficienthandover (HO) that is easier than the conventional inter-frequencyhandover (HO) can be carried out.

Common MAC Handover (HO) of Single Carrier Supported AMS according toHandover (HO) Procedure

FIGS. 10( a), 10(b) and 10(c) illustrate common MAC handover (HO)procedures of a single carrier AMS through a handover (HO) procedureaccording to one embodiment of the present invention. Variousembodiments illustrating that a single carrier supported AMS performsinter-carrier handover (HO) controlled by a common MAC will hereinafterbe described with reference to FIGS. 10( a), 10(b) and 10(c).

The term ‘common MAC handover’ described in the present invention meansa carrier change in which one carrier (i.e., a serving carrier)controlled by a common MAC is changed to another carrier (i.e., a targetcarrier) controlled by the same MAC as the common MAC, and brieflyrepresents handover (HO) between carriers controlled by a single commonMAC entity.

Common MAC handover having no network re-entry will hereinafter bedescribed with reference to FIG. 10( a). Referring to FIG. 10( a),according to either a handover request (AAI_MSHO-REQ) message (S1011)from a single carrier supported AMS or an unsolicited scheme, the ABScan transmit a handover command (AAI_BSHO-CMD) message to the AMSthrough a serving carrier (S-carrier) at step S1012. In response to theAAI_BSHO-CMD message, the single carrier supported AMS may transmit ahandover indication (AAI_HO-IND) message to the serving ABS (S-ABS) atstep S1013. The single carrier supported AMS may be disconnected fromthe ABS through the serving carrier (S-carrier) at a disconnection timedefined by the AAI_BSHO-CMD message at step S1014.

The target carrier (T-carrier) is arranged along with the servingcarrier (S-carrier) and the T-carrier and the S-carrier are controlledby the same common MAC, such that the ABS is able to pre-recognize allof MAC-associated information of the AMS managed through the single MAC.Therefore, transmission and reception of MAC-level rangingrequest/response (RNG-REQ/RSP) messages that need to be minimallycarried out between a target ABS (T-ABS) and the AMS may be omitted fromthe network re-entry procedure. Accordingly, according to thisembodiment of the present invention, the single carrier supported AMShaving received the AAI_BSHO-CMD message can directly perform handover(HO) at an action time defined by AAI_BSHO-CMD message and can exchangedata with the ABS at step S1015. In association with the abovedescription, it is necessary for the single carrier supported AMS torecognize the fact that a target carrier (T-carrier) is a carriercontained in the same common MAC as that of the serving carrier(S-carrier) prior to the beginning of the action time, and suchrecognition information may be transmitted to the AMS through either theAAI_BSHO-CMD message or the neighbor advertisement (AAI_NBR-ADV)message.

One embodiment that uses the AAI_HO-IND message as a confirmationmessage (also called a ‘confirm message’) will hereinafter be describedwith reference to FIG. 10( b). Referring to FIG. 10( b), according toeither a handover request (AAI_MSHO-REQ) message (S1021) received fromthe single carrier supported AMS or an unsolicited scheme, an ABS cantransmit a handover command (AAI_BSHO-CMD) message to the AMS through aserving carrier (S-carrier) at step S1022. After receiving theAAI_BSHO-CMD message from the ABS, the AMS may be disconnected from theABS through the serving carrier (S-carrier) at a disconnection time atstep S1023.

As previously stated above, the AAI_HO-IND message for use in theconventional handover procedure is optional, such that it may not betransmitted from the AMS to the ABS. In this case, assuming that noranging request (RNG-REQ) message is received from the AMS as describedin the above-mentioned embodiment, the AMS may immediately be handedover to the target carrier (T-carrier) without transmitting a MAC-levelconfirmation message associated with the AAI_BSHO-CMD message to theABS. In this case, assuming that the handover command (AAI_BSHO-CMD)message is damaged or lost, the loss of data may unavoidably occur.

Thus, in order to allow the ABS to confirm the completion of AMShandover, a confirmation message may be transmitted from the AMS to theABS. For the confirmation message, in the case where the single carriersupported AMS performs the common MAC handover (HO), the AMS maytransmit the AAI_HO-IND message as a response to the AAI_BSHO-CMDmessage to the ABS through the T-carrier (instead of the S-carrier)after the lapse of the action time at step S1024. In association withthe above description, in order to allow the AMS to transmit theAAI_HO-IND message to the ABS through the target carrier (T-carrier), anuplink (UL) grant from the ABS must be present at an action time. TheABS having received the AAI_HO-IND message through the target carrier(T-carrier) assumes that the single carrier supported AMS hassuccessfully performed the common MAC handover (HO), such that the ABScan transmit and receive data to and from the ABS through the targetcarrier (T-carrier) at step S1025.

A handover (HO) procedure that uses a Bandwidth Request (BR) or a CQIallocation/report will hereinafter be described with reference to FIG.10( c). Referring to FIG. 10( c), according to either an AAI_MSHO-REQmessage (S1031) received from the single carrier supported AMS or anunsolicited scheme, the ABS can transmit a handover command(AAI_BSHO-CMD) message to the AMS through the serving carrier(S-carrier) at step S1032. In response to the AAI_BSHO-CMD message, thesingle carrier supported AMS may transmit the AAI_HO-IND message to theserving ABS (S-ABS) at step S1033. The single carrier supported AMS maybe disconnected from the ABS through the serving carrier (S-carrier) ata disconnection time defined by the AAI_BSHO-CMD message at step S1034.

In accordance with the embodiment of the present invention, the AMS mayoptionally transmit the AAI_HO-IND message in the same manner as in theconventional handover (HO) procedure at step S1033. On the other hand,in order to confirm no loss of the AAI_HO-CMD message, the AMS for usein the embodiment of the present invention transmits a Bandwidth Request(BR) through the target carrier (T-carrier) at an action time at stepS1035, whereas the AMS for use in the conventional handover (HO)procedure transmits a ranging request (RNG-REQ) message instead of theBR through the target carrier (T-carrier) at such an action time.

Otherwise, in the case where the CQI report is used as a confirmationmessage, so as to allow the AMS to transmit the CQI report to the ABS,the ABS can allocate a CQI channel (CQICH) to the AMS through the targetcarrier (T-carrier) at the action time. The AMS can transmit the CQIreport through the CQICH allocated by the ABS at step S1035. The ABSreceives the CQI report through the target carrier (T-carrier), suchthat it can recognize that the AMS has successfully performed handover(HO).

If the ABS receives the BR or the CQI report from the AMS through thetarget carrier (T-carrier), the ABS can recognize that the AMS wassuccessfully handed over to the target carrier (T-carrier), and cantransmit and receive data to and from the AMS through the target carrier(T-carrier) at step S1036.

The AMS operation during the network re-entry from among the common MAChandover (HO) procedure will hereinafter be described with reference toFIG. 11. FIG. 11 illustrates additional AMS operations for use in acommon MAC handover that is applied to previous AMS operations for usein the conventional handover (HO) network re-entry procedure. Asdescribed above, a simpler handover in which a network re-entry processis omitted is applied to the common MAC handover (HO) process, and CQICHallocation performed by the target ABS (T-ABS) and a CQI report of theAMS are used such that no loss of the AAI_HO-CMD message can beconfirmed. As shown in FIG. 11, if the inter-frequency handover (HO)occurs in the common MAC at step S1101, the target ABS (T-ABS) allocatesa CQICH for the AMS through the target carrier (T-carrier) at an actiontime defined by the AAI_HO-CMD message, and the AMS can report a CQI forthe target carrier (T-carrier) at step S1102. During the common MAChandover (HO), transmission and reception of the AAI_RNG-REQ/RSPmessages may be omitted at step S1103. If the target ABS (T-ABS)receives the CQI report, the handover (HO) procedure can be completed atstep S1104.

Hereinafter, one embodiment in which the single carrier supported AMSperforms common MAC handover (HO) using the handover command(AAI_HO-CMD) message will be described in detail.

A conventional AAI_HO-CMD message can be defined as the following threemodes 0b00, 0b01 and 0b11.

-   -   0b00: Handover (HO) Command    -   0b01: Zone Switch Command from MZone to LZone    -   0b11: AMS HO request rejected (AMS in list unavailable)

Mode 0b00

In the case of the first mode 0b00, the AAI_HO-CMD message includes oneor more target ABSs (T-ABSs) and the following parameters. Theseparameters are as follows.

-   -   Handover Re-entry Mode (HO_Reentry_Mode), Disconnect Time        Offset, and Resource Retain Time (Resource_Retain_Time)

The following parameters are contained in each target ABS (T-ABS), and adetailed description thereof is as follows.

-   -   Target ABS ID, Action Time, CDMA ranging flag (CDMA_RNG_FLAG),        HO Process Optimization, Ranging Initiation Deadline, and        Service Level Prediction

The following parameter is contained in each ABS serving as amulti-carrier supported ABS, and a detailed description thereof is asfollows.

-   -   Physical Carrier Index (Physical_Carrier_Index)

The following parameter is contained in an AMS having the multi-carriercapability.

-   -   Multi-Carrier Handover Indication (MCHO_Indication)

Mode 0b01

In the case of the second mode 0b01, the AAI_HO-CMD message that is usedas a zone switch command from an MZone (i.e., a zone for supporting anew MS according to the IEEE 802.16m standard) to an LZone (i.e., a zonefor supporting a legacy MS according to the IEEE 802.16e standard)includes the following parameters. These parameters are as follows.

-   -   HO Re-entry Mode (HO_Reentry_Mode), Action Time, Resource Retain        Time (Resource_Retain_Time), CDMA Ranging Flag (CDMA_RNG_FLAG),        and LZone information

Mode 0b11

In the case of the third mode 0b11, the AAI_HO-CMD message does notinclude information on any target ABSs.

In accordance with one embodiment of the present invention, the commonMAC handover (HO) may be indicated through the HO process optimizationfield defined in the AAI_HO-CMD message of the first mode 0b00.

In association with the above description, the HO process optimizationfield for use in the conventional AAI_HO-CMD message can be defined asfollows.

-   -   For each bit location, a value of ‘0’ indicates that a related        re-entry management message is required, and a value of ‘1’        indicates that a re-entry MAC control message may be omitted.    -   Bit #0: Omission of AAI_SBC-REQ/RSP MAC control messages during        re-entry processing    -   Bit #1: Omission of a PKM authentication phase except a TEK        phase during current re-entry processing    -   Bit #2: Seamless HO    -   Bit #3: To Be Determined (TBD)

In this embodiment of the present invention, Bit #3, undefined in the HOprocessing optimization field, can be defined as follows.

-   -   Bit #3: Omission of AAI_RNG-REQ/RSP messages during common MAC        handover (HO) or re-entry processing

The AMS that receives the AAI_HO-CMD message including the HO processingoptimization field in which Bit #3 is set to ‘1’, can recognize that acommanded handover (HO) is a common MAC handover (HO).

On the other hand, since all the frequency channels controlled by thecommon MAC use the same BSID, the AMS confirms that a target carrier(T-carrier) has the same BSID as that of a serving carrier (S-carrier),such that it can recognize the presence or absence of the common MAChandover (HO). In association with the above description, the AMS maypre-recognize a BSID of the corresponding carrier through amulti-carrier advertisement (AAI_MC-ADV) message broadcast from the ABSor a neighbor advertisement (AAI_NBR-ADV) message. Therefore, if thetarget carrier (T-carrier) specified by the handover command(AAI_HO-CMD) message received in the AMS has the same BSID as that ofthe serving carrier (S-carrier), the AMS can implicitly recognize thatthe handover (HO) commanded by the AAI_HO-CMD message is a common MAChandover.

In accordance with another embodiment of the present invention, acarrier change command mode may be additionally defined in theabove-mentioned AAI_HO-CMD message. In other words, the AAI_HO-CMDmessage may be defined to have the following four modes 0b00, 0b01,0b10, and 0b11.

-   -   0b00: HO Command    -   0b01: Zone Switch Command from MZone to LZone    -   0b10: Carrier Change Command    -   0b11: AMS HO request rejected (AMS in list unavailable)

Mode 0b10

In the case of the third mode 0b10, the AAI_HO-CMD message may have thefollowing parameters. These parameters are as follows.

-   -   Physical_Carrier_Index of target carrier    -   Disconnection Time (e.g., this parameter may be set to a        specific time at which connection to a serving carrier        (S-carrier) may be severed)    -   Action time (e.g., this parameter may be set to a transmission        time of a confirmation message indicating successful carrier        change to a target carrier (T-carrier))    -   CDMA_RNG_FLAG    -   Dedicated CDMA ranging code/opportunity (this parameter may be        used when a CDMA_RNG_FLAG field is set to ‘1’)

A method for allowing a single carrier supported AMS to perform commonMAC handover (HO) using the above-mentioned handover command(AAI_HO-CMD) message according to one embodiment of the presentinvention will hereinafter be described with reference to FIG. 12.

Referring to FIG. 12, the AMS can receive the AAI_HO-CMD message havingthe mode of 0b01 from the ABS at step S1201. The AMS may transmit theAAI_HO-IND message to the ABS through the serving carrier (S-carrier)upon receiving the AAI_HO-CMD message from the ABS at step S1202. On theother hand, in the case where a handover indication (AAI_HO-IND) messageserving as a confirmation message for indicating successful handover(HO) to a target carrier (T-carrier) is transmitted through the targetcarrier (T-carrier), the transmission of the AAI_HO-IND message throughthe serving carrier (S-carrier) may be omitted as necessary.

The AMS is disconnected from the serving carrier (S-carrier) at adisconnection time defined by the AAI_HO-CMD message. If necessary, theAMS may perform synchronization and ranging (CDMA ranging or periodicranging) through the target carrier (T-carrier) at step S1203. Assumingthat the disconnection time is not defined, the connection to theserving carrier (S-carrier) may be severed at an action time, and theconfirmation message may be transmitted through the T-carrier.

The AMS may transmit a confirmation message (AAI_HO-IND, BR or CQIreport) through the target carrier (T-carrier) at the action timedefined by the AAI_HO-CMD message at step S1204. Through theconfirmation message, the ABS can confirm the successful carrier changeof the AMS. After the completion of transmission/reception of theconfirmation message, the AMS can transmit and receive data to and fromthe ABS through the target carrier (T-carrier) at step S1205.

Common MAC Handover (HO) of Single Carrier AMS According to CarrierManagement Procedure

FIG. 13 is a flowchart illustrating common MAC handover (HO) proceduresof a single carrier AMS through a multi-carrier associated MAC controlmessage according to one embodiment of the present invention. Oneembodiment wherein a single carrier AMS performs a carrier changeprocedure by interpreting a multi-carrier associated MAC control messagewill hereinafter be described with reference to FIG. 13.

The common MAC handover (HO) procedures described in FIG. 10 illustratevarious embodiments to be used when a single carrier AMS does notreceive/interpret a multi-carrier associated MAC message, such that theinter-frequency handover (HO) among carriers controlled by the commonMAC can be more easily performed than the conventional HO procedureusing the AAI_HO-CMD/IND messages.

On the other hand, the single carrier AMS may also have the capabilityto receive and interpret a multi-carrier associated MAC control message.As previously described in Table 1, in the case where the single carrierAMS has a multi-carrier capability of a basic multi-carrier (MC) mode,this means that the AMS can be aware of the ABS multi-carrier (MC)operation (that includes primary carrier change and the support of MCoperation associated optimization scanning). Such AMS capability may betransferred to the ABS through the AAI_REG-REQ message that istransmitted from the AMS to the ABS during the initial network entryprocedure.

In the case of the single carrier AMS, a carrier of the AMS can beeasily changed (or handed over) to one of the fully configured carrierscontrolled by the common MAC through the multi-carrier associated MACcontrol message (e.g., AAI_CM-CMD message). However, the single carrierAMS is simultaneously unable to employ a plurality of carriersdifferently from the multi-carrier AMS, such that one embodiment of thepresent invention proposes a new procedure different from the primarycarrier change procedure of the multi-carrier (MC) operation.

As described above, the carrier management command (AAI_CM-CMD) messageis a MAC control message that is used by the multi-carrier supported AMSso as to achieve not only secondary carrier management(activation/deactivation) but also primary carrier change. In themeantime, in the case of a single carrier AMS having the multi-carriercapability serving as a basic multi-carrier (MC) mode, the AMS canreceive physical indexes and setup information of all the availablecarriers supported by the ABS through a multi-carrier advertisement(AAI_MC-ADV) message broadcast from the ABS supporting multiplecarriers. That is, the single carrier AMS supporting the basic MC modecan be aware of information about all the carriers belonging to a cellthat is currently receiving the service. As previously stated in thedefinition of ‘Basic MC mode’, the single carrier AMS can receive theAAI_CM-CMD message from the ABS, and can recognize an exemplary case inwhich the action code of the AAI_CM-CMD message is set to ‘1’ (That is,the case of primary carrier change). Therefore, the single carrier AMSsupporting the basic MC mode can perform the carrier change procedureamong carriers controlled by the common MAC through the AAI_CM-CMDmessage.

Although the single carrier AMS supports the basic MC mode, it isconfigured to monitor only one carrier at an arbitrary time point, suchthat it is impossible for the carrier change procedure, that isperformed after the T-carrier activation in the same manner as in theprimary carrier change procedure of the multi-carrier AMS, to be appliedto the single carrier AMS.

In accordance with the embodiment of the present invention, the servingABS (S-ABS) can transmit the AAI_CM-CMD control message to the AMSthrough a current serving carrier (S-carrier) such that the AMS performscarrier change to one of the available fully configured carriersbelonging to the serving ABS (S-ABS) in response to the AAI_CM-CMDcontrol message. The assigned carrier cannot be assigned to the singlecarrier AMS, such that the target carrier (T-carrier) must be indicatedas one of the available fully configured carriers. If the single carrierAMS receives the AAI_CM-CMD message, it severs the control connectionthrough the serving carrier (S-carrier) and may perform carrier changeto a target fully configured carrier at an action time specified by theABS. The single carrier AMS can communicate with the ABS through onlyone carrier at an arbitrary time, such that it is necessary for theconnection on the S-carrier to first be severed, such that the singlecarrier AMS can communicate with the ABS through the target carrier(T-carrier). In addition, in the case where the ranging indicator or thededicated CDMA ranging flag is established in the AAI_CM-CMD message,the AMS can perform periodic ranging or dedicated ranging through thetarget carrier (T-carrier).

A method for controlling the single carrier AMS to perform a carrierchange procedure using the AAI_CM-CMD/IND messages according to oneembodiment of the present invention will hereinafter be described withreference to FIG. 13. Referring to FIG. 13, the single carrier AMS canreceive the AAI_CM-CMD message corresponding to the primary carrierchange having the action code of 1 from the ABS at step S1301. Inreference to the single carrier AMS, a target carrier (T-carrier)specified by the AAI_CM-CMD message may be defined to be a physicalcarrier index. The single carrier AMS does not receive the assignedcarrier from the ABS differently from the multi-carrier AMS, such thatthe logical carrier index indicating the assigned carrier is unable tobe used for the single carrier AMS. Otherwise, in order to indicate thetarget carrier (T-carrier) for all the AMSs, a physical carrier indexmay be used. In the meantime, a T-carrier indicator for use in themulti-carrier supported AMS may be one of the assigned fully configuredcarriers, and a logical carrier index may be used.

The AMS may transmit the AAI_CM-IND message in response to theAAI_CM-CMD message at step S1302. However, in the case where theAAI_CM-IND message is used as a confirmation message for carrier changeconfirmation, the transmission of the AAI_CM-IND message through theS-carrier may be omitted as necessary.

The AMS is disconnected from the serving carrier (S-carrier) at anaction time specified by the AAI_CM-CMD message, and may performsynchronization and ranging (CDMA dedicated ranging or periodic ranging)through the target carrier (T-carrier) as necessary, such that it canestablish the connection to the ABS through the target carrier(T-carrier) at step S1303. In this case, a disconnection time from theserving carrier (S-carrier) is not additionally established and the AMSdecides the action time to be the disconnection time, such that the AMSmay sever the connection to the serving carrier (S-carrier). Uponsuccessful completion of synchronization and ranging, the AMS transmitsthe AAI_CM-IND message through the target carrier (T-carrier) ortransmits a Bandwidth Request (BW Request) or a CQI report through thetarget carrier (T-carrier), such that it can inform the ABS of thesuccessful carrier change at step S1304.

In reference to the above description, a ‘Next State of Serving PrimaryCarrier’ field of a serving primary carrier (S-PC) from among fieldscontained in the AAI_CM-CMD message represents that an activation statusof a serving carrier (S-carrier) is changed to a deactivation status(i.e., value: 0) after the primary carrier change or the serving carrier(S-carrier) activation status is maintained (i.e., value: 1) after theprimary carrier change. In reference to the single carrier AMS, the‘Next State of Serving Primary Carrier’ field may be used as a rangingindicator field. If the ranging indicator field is set to ‘0’, thismeans that the ranging for the target carrier (T-carrier) is no longerrequired. In addition, if the ranging indicator field is set to ‘1’,this means that the periodic ranging of the target carrier (T-carrier)is required.

In contrast, the single carrier AMS not supporting carrier aggregationcan communicate with the ABS through only one carrier, such that theserving carrier (S-carrier) should always be deactivated upon completionof carrier change. Therefore, in accordance with one embodiment of thepresent invention, the ‘Next State of Serving Primary Carrier’ field mayalways be set to zero ‘0’ indicating a deactivation status. In thiscase, the ranging indicator field may be defined as an additional field.

Instead of performing the periodic ranging through the rangingindicator, a field for performing the dedicated ranging through CDMAcode/opportunity may be additionally defined in the AAI_CM-CMD message.In this case, a CDMA ranging flag (CDMA_RNG_FLAG) field may also bedefined in the AAI_CM-CMD message. If the CDMA_RNG_FLAG field for thetarget carrier (T-carrier) is set to ‘0’, this means that ranging is notrequired. If the CDMA_RNG_FLAG field for the target carrier (T-carrier)is set to ‘1’, this means that the dedicated ranging for the targetcarrier (T-carrier) is required. If the CDMA_RNG_FLAG field is set to‘1’, the dedicated CDMA ranging code/opportunity field may be containedin the AAI_CM-CMD message.

In accordance with this embodiment of the present invention, the commonMAC handover (HO) of the single carrier AMS can be carried out throughthe field contained in the currently defined AAI_CM-CMD message.Otherwise, in the case where the multi-carrier supported AMS has alimitation in simultaneously employing the serving carrier (S-carrier)and the target carrier (T-carrier) for the primary carrier change, theprimary carrier change may be carried out through the same procedures asthose of the present invention.

Some parameters of the AAI_CM-CMD message according to this embodimentof the present invention may be defined by the following Table 13.

TABLE 13 Size Field (bit) Description ... If (Action code == 1){ Thismessage is for primary carrier change.  Target carrier index [TBD]Target carrier index for primary carrier change If AMS only supportssingle carrier, this shall refer to the physical carrier index  ActionTime [TBD] LSB bits of Superframe number at the time to switch to thetarget carrier This value shall be set to the value more than theretransmission time for AAI_CM-CMD message AMS disconnects connectionwith serving carrier and performs synchronization and/or CDMA rangingprocedure with target carrier at this time. If (AMS == multicarriersupported AMS){ 1 ‘0’: Serving carrier will be deactivated after  Nextstate of serving primary carrier primary carrier change } ‘1’: Servingcarrier is kept active after primary carrier change If (AMS == singlecarrier supported AMS){ If AMS only supports single carrier, this fieldis  Ranging indicator used as ‘ranging indicator’ } Ranging indicatorfor target carrier ‘0’: No ranging is required for the target carrier‘1’: Periodic ranging is required for the target carrier } ...

Assuming that the T-carrier for the primary carrier change is alwaysindicated by a physical carrier index and the ranging indicator field isseparately defined, some parameters of the AAI_CM-CMD message may bedefined by the following Table 14.

TABLE 14 Size Field (bit) Description ... If (Action code == 1){ Thismessage is for primary carrier change.  Physical carrier index of Target6 Physical carrier index of target carrier

carrier 

for primary carrier change If the AMS supports multicarrier operation,the carrier shall be one of the assigned carriers.  Action Time 3 LSBbits of Superframe number at the time to switch to the target carrierThis value shall be set to the value more than the retransmission timefor AAI_CM-CMD message AMS disconnects connection with serving carrierand performs synchronization and/or CDMA ranging procedure with targetcarrier at this time.  Next state of serving primary carrier 1 ‘0’:Serving carrier will be deactivated after primary carrier change; If theAMS does not support carrier aggregation, this field shall be always setto ‘0’ ‘1’: Serving carrier is kept active after primary carrier change Ranging indicator 1 Ranging indicator for target carrier ‘0’: Noranging is required for the target carrier ‘1’: Periodic ranging isrequired for the target carrier } ...

Otherwise, instead of performing the periodic ranging through theranging indicator, a field for performing the dedicated ranging throughCDMA code/opportunity may be additionally defined in the AAI_CM-CMDmessage. In this case, a CDMA ranging flag (CDMA_RNG_FLAG) field mayalso be defined in the AAI_CM-CMD message. If the CDMA_RNG_FLAG fieldfor the target carrier (T-carrier) is set to ‘0’, this means thatranging is not required. If the CDMA_RNG_FLAG field for the targetcarrier (T-carrier) is set to ‘1’, this means that the dedicated rangingfor the target carrier (T-carrier) is required. If the CDMA_RNG_FLAGfield is set to ‘1’, the dedicated CDMA ranging code/opportunity fieldmay be contained in the AAI_CM-CMD message. In this case, someparameters of the AAI_CM-CMD message may be defined by the followingTable 15.

TABLE 15 Size Field (bit) Description ... If (Action code == 1){ Thismessage is for primary carrier change.  Physical carrier index of Target6 Physical carrier index of target carrier

carrier 

for primary carrier change If the AMS supports multicarrier operation,the carrier shall be one of the assigned carriers.  Action Time 3 LSBbits of Superframe number at the time to switch to the target carrierThis value shall be set to the value more than the retransmission timefor AAI_CM-CMD message AMS disconnects connection with serving carrierand performs synchronization and/or CDMA ranging procedure with targetcarrier at this time.  Next state of serving primary carrier 1 ‘0’:Serving carrier will be deactivated after primary carrier change; If theAMS does not support carrier aggregation, this field shall be always setto ‘0’ ‘1’: Serving carrier is kept active after primary carrier change CDMA_RNG_FLAG 1 CDMA Ranging flag for target carrier ‘0’: No ranging isrequired for the target carrier ‘1’: Dedicated ranging is required forthe target carrier  If (CDMA_RNG_FLAG == 1){ [TBD] These parameters maybe included when   Dedicated CDMA ranging CDMA_RNG_FLAG = 1  code/opportunity  } } ...

Procedures for controlling the single carrier AMS to perform a commonMAC handover (HO) using the carrier management control message accordingto one embodiment of the present invention will hereinafter be describedwith reference to FIG. 14.

In the procedure shown in FIG. 14( a), if the AAI_CM-CMD message isadapted to perform a carrier change of the single carrier AMS, an actioncode indicating the carrier change from among action codes of theAAI_CM-CMD message may be newly defined as, for example ‘11’. Inresponse to such an action code, the single carrier AMS can be aware ofa carrier change and can perform a necessary action associated with therecognized carrier change.

Referring to FIG. 14( a), the single carrier AMS can receive theAAI_CM-CMD message corresponding to the carrier change having an actioncode ‘11’ from the ABS at step S1411. In the case of the action code‘11’, the AAI_CM-CMD message may include a target carrier index, adisconnection time, an action time, and a ranging indicator.

In reference to the single carrier AMS, the target carrier (T-carrier)specified by the AAI_CM-CMD message may represent a physical carrierindex. The AMS may transmit the AAI_CM-IND message in response to theAAI_CM-CMD message at step S1412. However, in the case where theAAI_CM-IND message is used as a confirmation message for carrier changeconfirmation, the transmission of the AAI_CM-IND message through theserving carrier (S-carrier) may be omitted as necessary.

The AMS severs the connection to the serving carrier (S-carrier) at adisconnection time specified by the AAI_CM-CMD message, and may performsynchronization and ranging through the target carrier (T-carrier) asnecessary at step S1413. If the disconnection time is not defined,similar to the above-mentioned embodiment, the AMS severs the connectionto the serving carrier (S-carrier) at an action time specified by theAAI_CM-CMD message, and may perform synchronization and ranging throughthe target carrier (T-carrier).

The AMS may transmit the AAI_CM-IND message through the target carrier(T-carrier) at an action time specified by the AAI_CM-CMD message, ormay transmit a BR or a CQI report through the target carrier(T-carrier), such that it can inform the ABS of successful carrierchange at step S1414.

Some parameters of the AAI_CM-CMD message according to this embodimentof the present invention may be defined by the following Table 16.

TABLE 16 Size Field (bit) Description AAI_Carrier Management Commandmessage format( ){ Management Message Type 8 AAI_CM-CMD Action code 200: Secondary Carrier Management 01: Primary carrier change 10: CarrierSwitching 11: Carrier Change ... If (Action code == 11){ This message isfor carrier change of single carrier supported AMS  Target carrier index[TBD] Target carrier index for carrier change (refer to physical carrierindex)  Disconnection Time [TBD] LSB bits of Superframe number at thetime to switch to the target carrier. AMS shall disconnect connectionwith serving carrier at this time.  Action Time [TBD] LSB bits ofSuperframe number at the time to switch to the target carrier. AMS shalltransmit any confirm message to target carrier for successful carrierchange at this time.  Ranging indicator 1 Ranging indicator for targetcarrier ‘0’: No ranging is required for the target carrier ‘1’: Periodicranging is required for the target carrier } ...

In accordance with one embodiment in which dedicated ranging is usedwhen the action code of the AAI_CM-CMD message is defined as ‘11’, theCDMA_RNG_FLAG field is contained in the AAI_CM-CMD message. In addition,if the CDMA_RNG_FLAG field is set to ‘1’, the AAI_CM-CMD message mayfurther include a dedicated CDMA ranging code/opportunity field. Someparameters of the AAI_CM-CMD message may be defined by the followingTable 17.

TABLE 17 Size Field (bit) Description AAI_Carrier Management Commandmessage format( ){ Management Message Type 8 AAI_CM-CMD Action code 200: Secondary Carrier Management 01: Primary carrier change 10: CarrierSwitching 11: Carrier Change ... If (Action code == 11){ This message isfor carrier change of single carrier supported AMS  Target carrier index[TBD] Target carrier index for carrier change (refer to physical carrierindex)  Disconnection Time [TBD] LSB bits of Superframe number at thetime to switch to the target carrier. AMS shall disconnect connectionwith serving carrier at this time.  Action Time [TBD] LSB bits ofSuperframe number at the time to switch to the target carrier. AMS shalltransmit any confirm message to target carrier for successful carrierchange at this time.  CDMA_RNG_FLAG 1 CDMA Ranging flag for targetcarrier ‘0’: No ranging is required for the target carrier ‘1’:Dedicated ranging is required for the target carrier  If (CDMA_RNG_FLAG== 1){ [TBD] These parameters may be included when   Dedicated CDMAranging CDMA_RNG_FLAG = 1   code/opportunity  } } ...

Procedures depending on values of the above-mentioned CDMA_RNG_FLAGfield according to one embodiment of the present invention willhereinafter be described with reference to FIGS. 14( b) and 14(c).

An exemplary carrier change procedure to be used when the CDMA_RNG-FLAGfield is set to ‘0’ according to one embodiment of the present inventionwill hereinafter be described with reference to FIG. 14( b). Referringto FIG. 14( b), the single carrier AMS can receive the AAI_CM-CMDmessage corresponding to the carrier change having an action code ‘11’from the ABS at step S1421. In the case of the action code ‘11’, theAAI_CM-CMD message may include a target carrier index, a disconnectiontime, an action time, and a ranging indicator.

In reference to the single carrier AMS, the target carrier (T-carrier)specified by the AAI_CM-CMD message may represent a physical carrierindex. The AMS may transmit the AAI_CM-IND message in response to theAAI_CM-CMD message at step S1422. However, in the case where theAAI_CM-IND message is used as a confirmation message for carrier changeconfirmation, the transmission of the AAI_CM-IND message through theserving carrier (S-carrier) may be omitted as necessary.

The disconnection time specified by the AAI_CM-CMD message may be set toany time after the sum of one time consumed for the AMS to decode theAAI_CM-CMD message and the other time consumed for transmission of theAAI_CM-IND message. At the disconnection time, the AMS severs theconnection to the serving carrier (S-carrier) and may perform carrierchange from the serving carrier (S-carrier) to the target carrier(T-carrier) at step S1423.

An action time specified by the AAI_CM-CMD message when theCDMA_RNG_FLAG field is set to ‘0’ may be set to a predetermined periodof time in which the carrier change to the target carrier (T-carrier) issuccessfully performed and then the AMS transmits a confirmation message(AAI_CM-IND, BR or CQI report) through the target carrier (T-carrier) atstep S1424.

An exemplary carrier change procedure to be used when the CDMA_RNG-FLAGfield is set to ‘1’ according to one embodiment of the present inventionwill hereinafter be described with reference to FIG. 14( c). Steps S1431and S1432 in FIG. 14( c) are substantially identical to steps S1421 andS1422 to the exclusion of the CDMA_RNG_FLAG value in FIG. 14( b).

The disconnection time specified by the AAI_CM-CMD message may be set toany time after the sum of one time consumed for the AMS to decode theAAI_CM-CMD message and the other time consumed for transmission of theAAI_CM-IND message. At the disconnection time, the AMS severs theconnection to the serving carrier (S-carrier) and may performsynchronization and ranging through the target carrier (T-carrier) atstep S1433.

An action time specified by the AAI_CM-CMD message when theCDMA_RNG_FLAG value is set to ‘1’ may be set to a predetermined periodof time in which the AMS transmits a CDMA ranging code through thetarget carrier (T-carrier) such that CDMA ranging can be performedthrough the target carrier (T-carrier) at step S1434. In this case, inorder to establish synchronization with the target carrier (T-carrier)during the carrier change procedure after the disconnection time,ranging can be performed using the dedicated CDMA rangingcode/opportunity field received from the AAI_CM-CMD message.

In this case, a field of a predetermined deadline (i.e., target carrieractivation) to prepare for carrier change may be defined in theAAI_CM-CMD message. The carrier change readiness deadline may be set toa predetermined period of time from the beginning of the disconnectiontime to the end of T-carrier activation as necessary. Assuming that theCDMA ranging is successfully performed prior to the carrier changedeadline, the AMS may transmit a confirmation message (AAI_CM-IND, BR orCQI report) through the target carrier (T-carrier) at step S1435. In themeantime, assuming that the CDMA ranging results in a failure prior tothe carrier change deadline, the AMS and the ABS may restart the servicethrough the serving carrier (S-carrier).

Hereinafter, a variety of embodiments illustrating carrier change of asingle carrier supported AMS by means of a carrier management procedurewill be described in detail.

The carrier change procedure of the single carrier supported AMS can beseparately defined as follows.

For the purpose of load balancing, variable carrier channel quality orother factors, the ABS may command the AMS to change a current servingcarrier (S-carrier) to one of the available fully configured carriersbelonging to the ABS through the AAI_CM-CMD MAC control message of thecurrent S-carrier. If the single carrier supported AMS receives theAAI_CM-CMD MAC control message in which an action code is set to ‘1’,the AMS may transmit the AAI_CM-IND MAC control message prior to theaction time.

After the lapse of the action time, the AMS may perform a hardware reset(e.g., RF center frequency), and may switch to the target carrier(T-carrier). If the CDMA_RNG-FLAG field of the AAI_CM-CMD message is setto ‘1’, the AMS may perform dedicated ranging to the target carrier(T-carrier). Upon successful completion of dedicated ranging, the AMStransmits a bandwidth request (BR) indicating successful switching tothe target carrier (T-carrier) to the ABS. If the AMS receives uplinkdata to be transmitted, a general bandwidth request (BR) procedure isperformed. If the AMS does not have uplink data to be transmitted, a BRhaving the BR size of ‘0’ may be transmitted. Upon receiving the BR fromthe AMS, the ABS may transmit a control signal and data through thetarget carrier (T-carrier). In the case where the common MAC managesboth the serving carrier (S-carrier) and the target carrier (T-carrier),the network re-entry is not requested at the target carrier (T-carrier).Through the serving carrier (S-carrier), the ABS may provide systeminformation of the target carrier (T-carrier) different from the servingcarrier (S-carrier). The ABS may command the AMS to perform the primarycarrier change without scanning.

The AAI_CM-CMD MAC control message for carrier change may include aT-carrier index (indicating a physical carrier index), an action time,CDMA_RNG-FLAG, and a dedicated CDMA ranging code/opportunity. In thecase where the CDMA_RNG-FLAG field is set to ‘1’, the dedicated CDMAranging code/opportunity may be contained in the AAI_CM-CMD MAC controlmessage.

In the meantime, a method for defining a new action code and controllinga single carrier AMS to perform a common MAC carrier change (handover)using the AAI_CM-CMD message according to an embodiment of the presentinvention will hereinafter be described. In the AAI_CM-CMD message, anaction code that indicates a carrier change of the single carriersupported AMS may be set to ‘10’. In association with the action code‘10’, the AAI_CM-CMD message may further include a physical carrierindex of a target carrier (T-carrier), an action time field, aCDMA_RNG-FLAG field, and a dedicated CDMA ranging code/opportunityfield. Some parameters of the AAI_CM-CMD message can be defined by thefollowing Table 18.

TABLE 18 Size Field (bit) Description AAI_Carrier Management Commandmessage format( ){ Control Message Type 8 AAI_CM-CMD Action code 2 00:Secondary carrier management 01: Primary carrier change 10: Carrierchange for single carrier supported AMS 11: reserved ... If (Action code== 10){ This message is for carrier change for single carrier supportedAMS.  Physical carrier index of target carrier [TBD] Physical carrierindex of target carrier  Action Time [TBD] LSB bits of Superframe numberat the time to switch to the target carrier. AMS shall disconnectconnection with serving carrier at this time.  CDMA_RNG_FLAG 1 CDMARanging flag for target carrier ‘0’: No ranging is required for thetarget carrier ‘1’: Dedicated HO ranging is required for the targetcarrier  If (CDMA_RNG_FLAG == 1){   Dedicated CDMA ranging [TBD]code/opportunity  } } ...

Next, one embodiment for supporting the carrier change of the singlecarrier AMS by defining a new indication type field in the AAI_CM-CMDmessage will hereinafter be described in detail.

In accordance with this embodiment of the present invention, an actioncode ‘1’ indicating the primary carrier (P-carrier) change from amongaction codes of the AAI_CM-CMD message may be defined to represent‘carrier change’. Therefore, an indication type field for indicating theaction code of 1 may be defined and ‘P-Carrier Change/Carrier Change’fields depending on the AMS types (multi-carrier supported AMS: 0 andsingle carrier supported AMS: 1) may be respectively defined. Forexample, one case in which the AMS type is a single carrier supportedAMS is set to an indication type ‘1’, such that a physical carrier indexof a target carrier (T-carrier), an action time field, a CDMA_RNG_FLAGfield, and a dedicated CDMA ranging code/opportunity field can be newlydefined. In this case, some parameters of the AAI_CM-CMD message can bedefined by the following Table 19.

TABLE 19 Size Field (bit) Description AAI_Carrier Management Commandmessage format( ){ Control Message Type 8 AAI_CM-CMD Action code 1 0:Secondary carrier management 1: 

 Carrier change ... If (Action code == 1){ This message is for primarycarrier change. Indication Type 1 For AMS type 0: Primary carrier changefor multi-carrier supported AMS 1: Carrier change for single carriersupported AMS If(Indication Type == 0){ This message is for primarycarrier change for multi-carrier supported AMS.  Target carrier index[TBD] Target carrier index for primary carrier change  Action Time [TBD]LSB bits of Superframe number at the time to switch to the targetcarrier.  Next state of serving primary carrier 1 ‘0’: Serving carrierwill be deactivated after primary carrier change ‘1’: Serving carrier iskept active after primary carrier change } If(Indication Type == 1){This message is for carrier change for single carrier supported AMS. Physical carrier index of target carrier [TBD] Physical carrier indexof target carrier  Action Time [TBD] LSB bits of Superframe number atthe time to switch to the target carrier. AMS shall disconnectconnection with serving carrier at this time.  CDMA_RNG_FLAG 1 CDMARanging flag for target carrier ‘0’: No ranging is required for thetarget carrier ‘1’: Dedicated HO ranging is required for the targetcarrier  If (CDMA_RNG_FLAG == 1){   Dedicated CDMA ranging [TBD]code/opportunity  } } ...

In reference to the indication types ‘0’ and ‘1’ for use in theabove-mentioned case of the action code ‘1’, a target carrier indexfield and an action time field are shared. In reference to theindication type ‘0’ (indicating a multi-carrier supported AMS), the nextstatus field (Next State of Serving Primary Carrier) is defined. Inreference to the indication type ‘1’ (indicating a single carriersupported AMS), the CDMA_RNG_FLAG field and the dedicated CDMA rangingcode/opportunity field may be defined. In this case, some parameters ofthe AAI_CM-CMD message can be defined by the following Table 20.

TABLE 20 Size Field (bit) Description AAI_Carrier Management Commandmessage format( ){ Control Message Type 8 AAI_CM-CMD Action code 1 0:Secondary carrier management 1: 

 Carrier change ... If (Action code == 1){ This message is for 

 carrier change. Target carrier index [TBD] Target carrier index forprimary carrier change Action Time [TBD] LSB bits of Superframe numberat the time to switch to the target carrier. Indication Type 1 For AMStype 0: Primary carrier change for multi-carrier supported AMS 1:Carrier change for single carrier supported AMS If(Indication Type ==0){ This message is for primary carrier change for multi-carriersupported AMS. Next state of serving primary carrier 1 ‘0’: Servingcarrier will be deactivated after primary carrier change ‘1’: Servingcarrier is kept active after primary carrier change } If(Indication Type== 1){ This message is for carrier change for single carrier supportedAMS. CDMA_RNG_FLAG 1 CDMA Ranging flag for target carrier ‘0’: Noranging is required for the target carrier ‘1’: Dedicated HO ranging isrequired for the target carrier  If (CDMA_RNG_FLAG == 1){ [TBD]  Dedicated CDMA ranging code/opportunity  } } ...

In the above-mentioned embodiments, the periodic ranging instead of thededicated CDMA ranging may be carried out, and the action time may beset to a value higher than that of a retransmission time of theAAI_CM-CMD message.

Next, a network entry procedure for use in a multi-carrier operationaccording to one embodiment of the present invention will hereinafter bedescribed in detail.

As previously stated above, the network entry in a multi-carrier mode isbasically identical to that of the single-carrier mode, and the supportof the multi-carrier mode can be displayed during the registrationprocedure of the ABS and the AMS. During the initial network entry, theAMS transmits an advanced air interface registration request(AAI_REG-REQ) message to the ABS such that the AMS can inform the ABSthat the AMS supports multi-carrier transmission. The ABS can indicatewhether there is a supported one among multi-carrier modes of the AMSthrough an advanced air interface registration response (AAI_REG-RSP)message. In reference to multi-carrier capability of the ABS and theAMS, it is assumed that the ABS and the AMS do not support themulti-carrier (MC) mode (i.e., the ABS and the AMS have no MC modes).This assumption may correspond to an exemplary case in which a 2-bitcode of the advanced air interface registration request/response(AAI_REG REQ/RSP) message is set to ‘00’. In this case, the AMSinitialization operation for use in the network entry procedure willhereinafter be described with reference to FIG. 15.

Referring to FIG. 15, the embodiment of the present invention candetermine whether the ABS has the capability of no MC mode at step S1504after performing the network entry step S1501, the provisionedconnection establishment step S1502, and the operation step S1503,whereas the conventional AMS initialization operation determines whetherthe ABS and the AMS support the common MC mode after performing thenetwork entry step S1501, the provisioned connection establishment stepS1502, and the operation step S1503. If the ABS has the capability of noMC mode, the AMS initialization may be performed according to theprocedure defined in a single carrier at step S1505. If the ABS hasmulti-carrier (MC) capability (e.g., multi-carrier (MC) aggregationmode, multi-carrier (MC) switching mode, etc.) other than no MC mode, itis determined whether the AMS receives a multi-carrier advertisement(AAI_MC-ADV) message from the ABS at step S1506. If the AMS has receivedthe AAI_MC-ADV message from the ABS at step S1506, it is determinedwhether the multi-carrier capability of the AMS is ‘no MC mode’ at stepS1507.

Although the AMS has no MC mode, the AMS receives and interprets themulti-carrier MAC control message as previously described in theembodiment of the present invention, such that it can carry out thecommon MAC handover (HO) procedure. In other words, the AMS of no MCmode receives the AAI_MC-ADV message, such that it is ready to update MCinformation provided from the ABS or receive the carrier managementcommand (AAI_CM-CMD) message at step S1508. On the other hand, in thecase where the AMS has MC capability (e.g., multi-carrier (MC)aggregation mode, multi-carrier (MC) switching mode, etc.) other than noMC mode, the AMS and the ABS are ready for a multi-carrier (MC)operation through transmission/reception of the AAI_MC-REQ/RSP messagesat steps S1509 to S1511.

Otherwise, as previously described in Table 1, a basic MC mode fromamong the MC capability is defined and the single carrier AMS receivesand interprets the MC MAC message, such that the single carrier AMS isable to perform the common MAC handover (HO). The basic MC mode meansthat the AMS is able to be aware of the MC operation (including theprimary carrier change and the support of MC operation associatedoptimization scanning) of the ABS. In this case, the AMS initializationoperation will hereinafter be described with reference to FIG. 16.

Steps S1601 to S1606 of FIG. 16 are identical to steps S1501 to A1506 ofFIG. 15, and as such identical parts will herein be omitted forconvenience of description. Upon receiving the AAI_MC-ADV message fromthe ABS, it can be determined whether the AMS supports the basic MC modeat step S1607. If the AMS supports the basic MC mode, the AMS can beaware of the MC operation of the ABS, such that the AMS and the ABS areready for the MC operation without additional operations at step S1610.If the AMS receives MC capability other than the basic MC mode, the AMSand the ABS are ready for the MC operation throughtransmission/reception of the AAI_MC-REQ/RSP message at steps S1608 toS1610.

Next, one embodiment associated with the primary carrier change in thecase of using the AMS that is operated in the carrier aggregation modewill hereinafter be described in detail.

In accordance with the conventional primary carrier change procedure, ifa target carrier (T-carrier) is one of deactivated carriers, the AMS ofthe carrier aggregation mode has to perform the primary carrier changeafter severing the connection to the serving carrier (S-carrier), andhas to inform the ABS of T-carrier readiness by transmitting a BR or thelike to the ABS.

However, as previously stated in the above description, the currentlydefined carrier aggregation means an MC mode in which the AMS maintainsthe connection to a physical layer, monitors control signaling on aprimary carrier, and at the same time processes data on the secondarycarrier. The range of allocating resources to the AMS may cover aprimary carrier and a plurality of secondary carriers. A link adaptationfeedback mechanism includes measurement related to both the primarycarrier and the secondary carrier. In the MC aggregation mode, accordingto system load (i.e., static/dynamic load balancing), peak data rate, ora QoS request, the system may asymmetrically allocate secondary carriersto the AMS via downlink and/or uplink.

In this way, the carrier aggregation mode AMS can maintain the physicallayer connection through one or more carriers. Therefore, although thetarget carrier (T-carrier) is one of the deactivated carriers, the AMSneed not sever the connection to the serving primary carrier (S-PC) atan action time in order to achieve the primary carrier change. The ABSmay first activate a deactivated target carrier (T-carrier) prior to theexecution of the primary carrier change.

Therefore, in reference to the primary carrier change, the followingprocedures may also be used. If the AMS is in the carrier aggregationmode, the target carrier (T-carrier) may be one of the fully configuredcarriers, and the AMS may receive data and a control signal through thetarget carrier (T-carrier) immediately after performing the switching atan action time specified by the ABS. If the target carrier (T-carrier)is one of the deactivated secondary carriers, the ABS may transmit theAAI_CM-CMD message associated with the primary carrier change to the AMSafter activating the target carrier (T-carrier).

FIG. 17 is a block diagram illustrating an Advanced Mobile Station (AMS)according to the present invention.

Referring to FIG. 17, the AMS may include a reception (Rx) module 1710,a transmission (Tx) module 1720, a processor 1730, and a memory 1740.The reception (Rx) module 1710 may receive various signals, data,information, etc. from an external part such as an Advanced Base Station(ABS). The transmission (Tx) module 1720 may transmit various signals,data, information, etc. to the ABS or the like.

The processor 1730 may receive an advanced air interface carriermanagement command (AAI_CM-CMD) message that includes not only an actioncode for carrier management but also a polling bit, from the ABS throughthe reception (Rx) module 1710. In this case, the polling bit iscontained in a MAC Control Extended Header (MCEH) so that it canindicate whether or not an acknowledgement (ACK) message is needed. Ifthe AAI_CM-CMD message is successfully received and the polling bit isset to ‘1’, the processor 1730 can transmit an ACK message for theAAI_CM-CMD message to the ABS through the transmission (Tx) module 1720,and can transmit an AAI carrier management indication (AAI_CM-IND)message corresponding to the action code of the AAI_CM-CMD message tothe ABS through the transmission (Tx) module 1720.

The processor 1730 may arithmetically perform processing of informationreceived in the AMS, information to be transmitted externally, and thelike. The memory 1740 may store arithmetically-processed information fora predetermined time, and be replaced with any other constituent elementsuch as a buffer (not shown).

FIG. 18 is a block diagram illustrating an ABS according to the presentinvention.

Referring to FIG. 18, the ABS may include a reception (Rx) module 1810,a transmission (Tx) module 1820, a processor 1830, and a memory 1840.The reception (Rx) module 1810 may receive various signals, data,information, etc. from an external part such as an AMS. The transmission(Tx) module 1820 may transmit various signals, data, information, etc.to the AMS or the like.

The processor 1830 may transmit an AAI_CM-CMD message that includes notonly an action code for carrier management but also a polling bit, tothe AMS through the transmission (Tx) module 1820. In this case, thepolling bit is contained in a MAC Control Extended Header (MCEH) so thatit can indicate whether or not an acknowledgement (ACK) message isneeded. If the AAI_CM-CMD message is successfully received by the AMSand the polling bit is set to ‘1’, the processor 1830 can allow an ACKmessage for the AAI_CM-CMD message transmitted from the AMS to bereceived through the reception (Rx) module 1810, and can receive anAAI_CM-IND message corresponding to the action code of the AAI_CM-CMDmessage from the AMS.

The processor 1830 may arithmetically perform processing of informationreceived in the base station, information to be transmitted externally,and the like. The memory 1840 may store arithmetically-processedinformation for a predetermined time, and be replaced with any otherconstituent element such as a buffer (not shown).

Exemplary embodiments of the present invention may be achieved byvarious means, for example, hardware, firmware, software, or acombination thereof.

In a hardware configuration, the methods according to exemplaryembodiments of the present invention may be achieved by one or moreApplication Specific Integrated Circuits (ASICs), Digital SignalProcessors (DSPs), Digital Signal Processing Devices (DSPDs),Programmable Logic Devices (PLDs), Field Programmable Gate Arrays(FPGAs), processors, controllers, microcontrollers, microprocessors,etc.

In a firmware or software configuration, the methods according to theexemplary embodiments of the present invention may be implemented in theform of a module, a procedure, a function, etc. performing theabove-described functions or operations. Software code may be stored ina memory unit and executed by a processor. The memory unit is located atthe interior or exterior of the processor and may transmit and receivedata to and from the processor via various known means.

The detailed description of the exemplary embodiments of the presentinvention has been given to enable those skilled in the art to implementand practice the invention. Although the invention has been describedwith reference to the exemplary embodiments, those skilled in the artwill appreciate that various modifications and variations can be made inthe present invention without departing from the spirit or scope of theinvention described in the appended claims. For example, those skilledin the art may use each construction described in the above embodimentsin combination with each other. Accordingly, the invention should not belimited to the specific embodiments described herein, but should beaccorded the broadest scope consistent with the principles and novelfeatures disclosed herein.

Those skilled in the art will appreciate that the present invention maybe carried out in other specific ways than those set forth hereinwithout departing from the spirit and essential characteristics of thepresent invention. The above exemplary embodiments are therefore to beconstrued in all aspects as illustrative and not restrictive. The scopeof the invention should be determined by the appended claims and theirlegal equivalents, not by the above description, and all changes comingwithin the meaning and equivalency range of the appended claims areintended to be embraced therein. Also, it will be obvious to thoseskilled in the art that claims that are not explicitly cited in theappended claims may be presented in combination as an exemplaryembodiment of the present invention or included as a new claim bysubsequent amendment after the application is filed.

The exemplary embodiments of the present invention are applicable tovarious wireless access systems. The exemplary embodiments of thepresent invention have the following effects. In association with acarrier management procedure for use in a multi-carrier supportedwireless communication system, the embodiment of the present inventionprovides a method for effectively transmitting a carrier managementmessage and a method for effectively performing carrier management. Inassociation with a multi-carrier supported wireless communicationsystem, the embodiment of the present invention provides an effectivecarrier change method of a single-carrier supported MS.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the spirit or scope of the invention. Thus, it isintended that the present invention cover the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

What is claimed is:
 1. A method for a mobile station to perform carriermanagement procedure with a base station supporting multiple carriers,the method comprising: receiving a carrier management command messagefrom the base station, the carrier management command message includingan action code for carrier management and a polling bit in a MAC ControlExtended Header (MCEH) indicating whether an acknowledgement message isrequired; transmitting the acknowledgement message in response to thecarrier management command message to the base station when the carriermanagement command message is successfully received and the polling bitis set to 1; and transmitting a carrier management indication message,corresponding to the action code included in the carrier managementcommand message, to the base station, wherein the action code indicatesa primary carrier change or a secondary carrier management, and wherein,if the action code indicates the primary carrier change, theacknowledgement message in response to the carrier management commandmessage is transmitted on a serving primary carrier of the base station,and the carrier management indication message is transmitted on a targetprimary carrier of the base station.
 2. The method according to claim 1,wherein the carrier management indication message is transmitted to thebase station to inform the base station that a target carrier indicatedby the carrier management command message is ready for signaltransmission and reception.
 3. The method according to claim 1, whereinthe acknowledgement message is a message acknowledgement (AAI_MSG-ACK)message or a message acknowledgement extended header (MAEH).
 4. Themethod according to claim 1, wherein, if the action code indicates theprimary carrier change, the carrier management indication message istransmitted on a target primary carrier of the base station when theprimary carrier change is successful, and the carrier managementindication message is transmitted on a serving primary carrier of thebase station when the primary carrier change is not successful.
 5. Themethod according to claim 4, wherein the carrier management indicationmessage is transmitted through band request on the serving primarycarrier of the base station when the primary carrier change is notsuccessful and the serving primary carrier is deactivated.
 6. A methodfor a base station supporting multiple carriers to perform carriermanagement procedure with a mobile station, the method comprising:transmitting a carrier management command message to the mobile station,the carrier management command message including an action code forcarrier management and a polling bit in a MAC Control Extended Header(MCEH) indicating whether an acknowledgement message is required;receiving the acknowledgement message in response to the carriermanagement command message from the mobile station when the carriermanagement command message is successfully received by the mobilestation and the polling bit is set to 1; and receiving a carriermanagement indication message, corresponding to the action code includedin the carrier management command message, from the mobile station,wherein the action code indicates a primary carrier change or asecondary carrier management, and wherein, if the action code indicatesthe primary carrier change, the acknowledgement message in response tothe carrier management command message is transmitted on a servingprimary carrier of the base station, and the carrier managementindication message is transmitted on a target primary carrier of thebase station.
 7. The method according to claim 6, starting aretransmission timer at a transmission time of the carrier managementcommand message; stopping the retransmission timer and performing anoperation corresponding to the action code when the acknowledgementmessage is received prior to the expiration of the retransmission timer;and retransmitting the carrier management command message when noacknowledgement message is received prior to the expiration of theretransmission timer.
 8. The method according to claim 6, wherein thecarrier management indication message is received from the mobilestation to inform the base station that a target carrier indicated bythe carrier management command message is ready for signal transmissionand reception.
 9. The method according to claim 6, wherein theacknowledgement message is a message acknowledgement (AAI_MSG-ACK)message or a message acknowledgement extended header (MAEH).
 10. Themethod according to claim 6, wherein, if the action code indicates theprimary carrier change, the carrier management indication message isreceived on a target primary carrier from the mobile station when theprimary carrier change is successful, and the carrier managementindication message is received on a serving primary carrier from themobile station when the primary carrier change is not successful. 11.The method according to claim 10, wherein the carrier managementindication message is received through band request on the servingprimary carrier from the mobile station when the primary carrier changeis not successful and the serving primary carrier is deactivated.
 12. Amobile station for performing a carrier management procedure with a basestation supporting multiple carriers, the mobile station comprising: areception module; a transmission module; and a processor configured to:control the reception module to receive a carrier management commandmessage from the base station, the carrier management command messageincluding an action code for carrier management and a polling bit in aMAC Control Extended Header (MCEH) indicating whether an acknowledgementmessage is required, control the transmission module to transmit theacknowledgement message in response to the carrier management commandmessage to the base station when the carrier management command messageis successfully received and the polling bit is set to 1, control themobile station to perform carrier management operation based on thecarrier management command message, and control the transmission moduleto transmit a carrier management indication message, corresponding tothe action code included in the carrier management command message, tothe base station, and wherein the action code indicates primary carrierchange or secondary carrier management, and wherein, if the action codeindicates the primary carrier change, the acknowledgement message inresponse to the carrier management command message is transmitted on aserving primary carrier of the base station, and the carrier managementindication message is transmitted on a target primary carrier of thebase station.